If the occurrence of Citrus ichangensis (Ch'êng chou chih _??_) in Naga Hills, Assam, is to be justified, the East Himalayan foothill region should in-volve every representative of Citrus subgenera and sections except the monotypic Citrus madurensis (Chin chü _??_) of the section PSEUDOFORTUNELLA of possible garden origin. It's presumable that the origin of the genus Citrus is quite analog-ous to the creation of unifoliolate and solitary-flow-ered Citropsis Tanakae from other pinnate (or tri-foliolate) and paniculate (or racemose) members of the genus in the comparatively cooler region of Africa, and that of northernmost Severinia buxifolia (Kou chü _??_) of similar status from tropical mem-bers of the same genus having distinct inflores-cence. In such circumstances, some agency must have been existed in Eastern Asia several thousand years ago to drop the characters of compound leaf and inflorescence, leaving possible remainder represented by Poncirus trifoliata (Ju chou chih _??_) in the Yangtze valley of interior China. The origin of the subgenus METACITRUS, therefore, must have happened at the stage when paniculate subgenus ARCHICITRUS lost the inflorescence, as in the case of Citrus ichangensis from the section PAPEDA, like Citrus latipes, C. Combara of Eastern Himalaya. From the fact that the PAPEDA group and the section OSMOCITRUS occupy the broadest area of Citrus distribution, a considerable period must have elasped while the genus is represented only by these two sections of plants, undoubtedly giving rise to its start from Assam and its adjacent territory.
Although sect. ACRUMEN approaches most to OSMOCITRUS and both territories of Assam and the Yangtze Valley have definite representatives like Citrus indica and Chü _??_ (still unnamed), its repeated sporadic occurrences throughout the Pacifi ter-ritories may prove its very late origin, somewhat earlier than that of the genus Fortunella, without the direct link to OSMOCITRUS. After PAPEDA had become perfectly adapted to the tropical climate, it must have found the way to transform into the Contribution No. 6, from Tanaka Institute of Cit-riculture and Horticultual Science, College of Agriculture. University or Osaka Prefecture lime (sect. LIMONELLUS) and the shaddock (sect. CEPHALOCITRUS) by either thinning or thicken-ing of pericarp and a considerable elongation of pulp vesicles with the change of contents (the loss of acrid oil). This evolution must have occurred during their southward move to the Pacific Ocean from Himalaya, as evidenced by the fact that the former still grows wild in Malay Peninsula and the latter penetrates deep into East Himalayan foothills and interior China, recorded by men at least 2500 years ago.
In the next stage, the transformation of LIMONELLUS must have been directed toward the gain of strong citral aroma without the change of rind texture, intensified anthocyanin pigmentation and the fruit elongation, together with the complete loss of petiole wing. This brought out the small citron (Citrus limonimedica) and the lemon (C. Limon), representing sect. CITROPHORUM, and in taking mainly westward advancing route along the Himalaya range, it gave birth to the sweet lime (C. limettioides), Galgal (C. pseudolimon, n. sp.), Galgal Large (C. macrolimon, n. sp.), etc., but it left very important footprint in Assam in the form of closely related Citrus Limonia and C. Jambhiri. Undoubtedly both sour and sweet oranges (sect. AURANTIUM) are the direct descendants of the shaddock, having secure natural habitat in Assam, and posessing stabilized globose fruit with a great advancement of carotenoid pigmentation

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1. Using breeding veils for soil insect, the authors bred citrus ground mealy bugs to know their ecological characters, and investigated relationship between their density and the presence of straw mulch under mandarin orange trees at the damaged orchard, and also their resistibility against agricul-tural chemicals, to propose their effective control method suggested by results of these experiments.
2. The optimum margin of temperature and water content of saw-dust where the bug is bred (shown in percentage against water capacity) was found to range between 15_??_25°C of temperature and 27.6_??_52.5% water content, and its range was comparatively narrow.
In case of wireworms (Melanotus caudex LEWIS) breeding, it ranged between 10_??_25°C of temperature and 27.6_??_89.4% of water content; in case of Japa-nese beetles (Popillia japonica NEWMAN) in larval stage, it was between 10_??_30°C of temperature and 19.1_??_93.1% of water content.
The optimum temperature to breed citrus ground mealy bugs was the middle between both kinds of species, but the condition where water content of saw-dust is exceedingly less than in cases of both insects was suited to breeding of this one.
3. As water content of saw-dust increased the mortality of this insect increased, and in case of 100% water content no living insect completely existed in saw-dust; on the other side they came up to soil surface when the water content increased than 52.5%; and its tendency was remarkable as water content increased.
4. Because injurious insects died as water content increases, the authors investigated water content of soil under rotten straw mulch at damaged orchards. Water content of these soils showed nearly 100% even a few days after rainfall, which leads the authors to presume that the straw mulch over, the orchards is useful to control this insect.
5. Experiments on suspected relation between their density and the presence of straw mulch were carried out. In case of covering the whole orchards with straw mulch, the density of this insect was much less than that of no covering at the same damaged field; its damage was rather negligible.
6. In Fujieda district (Shizuoka Prefecture), damaged orchards were situated only at a slope land, and their management was bad: there was scarcely any cover of straw mulch, mandarin orange trees spread their shallow roots just under soil surface, and tea trees were planted under them.
7. The resistibility of this insect against agricultural chemicals was very weak; the insecticidual effects of calcium cyamide and tobacco dust were comparatively strong.
8. The authors suggest the following method for its successful controlling. After cleaning the soil surface of damaged orchards, and dusting with non-phytotoxicitic insecticide having a long residual-effect, the whole surface of orchards must be covered with thick straw mulch, because the insect con-cerned dies or comes up to the soil surface with increase in water content of soil.

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1. Cold storage tests of canning peaches were con-ducted in C-class storage houses in which tempera-ture was maintained between 0 and 5°C in 1956 and 1957. The varieties used in the tests were Kanto No. 2, No. 12 and No. 14.
2. Peaches stored for three weeks in the cold storage houses lost about 10 percent of their fresh weight. As no increase was obtained in the ratio of canned product to the packed flesh of stored peaches as compared with fresh ones, the loss in weight during cold storage was found to be net loss in canned product.
3. The longer the peaches were kept in cold storage, the more the deterioration in their flavor was. Off flavor was detected in the peaches stored for long period, though it was not clear that the off flavor was induced by physiological change in the fruits or by the conditions of the cold storage houses.
4. Among the varieties tested, Kanto No. 12 was. best in keeping quality, while no difference in keeping quality was found between the other two vari-eties.
5. The safe range of cold storage period of canning peaches during which their canning quality was retained without deterioration was 2_??_3 weeks, though it might be varied depending on the conditions of the storage house, handling method of fresh fruits before storing, and variety of canning peach.

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Some examples of abnormal leaves and abnormal tillerings observed in Welsh onion are reported. It may be summarized as follows:
1. Several rare cases where abnormal leaves having two laminae on a leaf sheath were observed in var. Iwatsuki, Kaga-Ippon, Asaki-Kujyo and Matsu-moto-Ippon. These were designated as “di-lamina leaf”. Almost all of these leaves were formed on the second or third node after the first tiller occurred.
As shown in Fig. 5, di-lamina leaves may be di-vided into three fundamental types by the arrange-ment of laminae.
2. When the n-th leaf was dwarf and its develop-ment was very slow, the emerging date of n-th leaf was frequently later than that of (n+1)th leaf in the normal order of emergence.
Examples of such cases were occasionally observed on the first leaf of tillers or new vegetative axil-lary buds.
3. Although the normal tillering bud of Welsh onion generally appears singly on a node, occasional-ly two or more tillering buds appeared on the same node. This abnormal phenomenon was designated as “poly-tillering”.
The poly-tillerings were observed rarely on the nodes of normal leaves, but more frequently on the nodes of di-lamina leaves.
Almost all of these poly-tillerings were formed on the first or second node after the first tiller occurred.
4. Sometimes, the development of tillering bud was so slow that the tiller appeared too late from the leaf sheath of preceding node for the normal tiller. These abnormal tillers may be divided into the following two types:
a) Only the first leaf is dwarf, but the second and subsequent leaves show a normal develop-ment.
b) All leaves of tiller are dwarf.
5. At times the abnormal tillers which developed the first leaf alone were observed. These examples were frequently observed in the last stage of the growing season.

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Experiment were carried out to clarify the effects of nitrogen supplied for the various stages from transplanting to harvesting time, on the growth and yield of onions in the sand culture. In both 1952 and 1955, onion seedlings (Yellow Danvers sown early in September) were transplanted late in No-vember and harvested late in next June, Results obtained were as follows.
1. The bulb yields of plants which were stopped nitrogen supply since middle or late in May (completing stage of top growth) were equal to, or rather exceeded that of control plants supplied with nitro-gen until harvesting time. Plants which were dis-continued nitrogen supply since middle or late in April (beginning stage of bulb thickening), were decreased to some degree in both top growth and bulb yield. And in the treatments in which nitrogen sup-ply were discontinued on and before middle or late in March (beginning stage of top growth), top growth and bulb yields were reduced remarkably, and their bulbs were round-shaped in contrast with flatshaped in the control.
2. Plants which were withheld nitrogen supply until late in February or early in March, and since then supplied with nitrogen, recovered their retar-dation of top growth rapidly and their bulb yields made no great difference compared with that of control. But when nitrogen supply was withheld until late in March, or late in April, bulb yields in these treatments could not catch up with that of control until harvesting time.
3. The treatments of cutting off the nitrogen sup-ply for about one month in the various stages of growth, had no effect on bulb yields at harvesting time.
4. In the tops of control plants, nitrogen and dry matter contents were lower until late in Febru-ary, and increased from Mach to May, especially the increment in April was remarkable. In the bulbs, nitrogen contents increased rapidly together with dry matter contents from middle or late in April, and continued to increase until harvesting time.
5. From results obtained, it is concluded that nitrogen supply from middle or late in March to middle or late in May is most important for growth and yield of onion, while nitrogen supply after late in May, or before early in March is not so import-ant as that for the above-mentioned period.

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1. The authors conducted the experiment in order to study the effectiveness of foliage sprays containing nutrients and growth regulators for preventing the occurrence of “pithy tissue” in Rapid Red radish.
2. The plants sprayed three times with 3% solution of Yogen No. 2 (containg N, P, and K) showed the same degree of pithyness as in the untreated ones, although the growth of the tops and roots was superior to that of the plants treated with other ways. In the plot sprayed twice with 10ppm solution of NAA, we found a decrease of the occurrence of “pithy tissue”, while the corpulency of their roots was not much less than that in the untreated ones, down to the latter stage of growth. These results show the higher practical value of these two treatments in the prevention of the occurrence of “pithy tissue”.
3. We also found the preventive effect in spraying three times with a mixed solution of 3% of Yogen No. 2 and 50ppm of gibberellin, but its effect was not so great as in the sprays of Yogen No. 2 alone.
The use of 50ppm solution of gibberellin cannot be recommended as practical use, because it gave an inferior corpulency of the root in spite of less occurrence of “pithy tissue”.
4. The plot treated twice with 10ppm solution of TIBA showed no recognizable difference in growth as compared with the untreated one, except that it actually promoted the occurence of “pithy tissue” In the case sprayed twice with 70ppm solution of MH, not only was the corpulency of the root hindered, but also the occurrence of “pithy tissue”. was tended to be promoted
5. Considering the result that every treatment which had a preventive effect upon the occurrence of “pithy tissues”, also caused growth of leaves and possibly an increase in the assimilation capacity of leaves, may be concluded that the spray improved the condition of the leaves, thus augmenting the nutrient supply to the roots, and decreased the pithyness.
On the other hand, the cause of the promotion of the occurrence of “pithy tissue” by spraying of TIBA and MH cannot be ascribed to the process of the occurrence of “pithy tissue” which had been explained in the previous reports, but rather to the direct action of them as anti-auxins.

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1. The studies were undertaken in 1955 at Kurume to make a survey of the bolting period, the flowering period, the form of ramification, the yield and germination percentage of the carrot seed using twelve leading varieties which are cultivated commonly in Japan.
2. The varieties cultivated in the southern part of Japan (Yokono-sanzun, Nagasaki-gosun, Kuroda-gosun and Tohsoh) showed the earlier habit in bolting and flowering period, the larger yield and better germination of seeds than the northern varieties(Early Scarlet Horn, Senko-sanzun, Chanteney, Ogatagosun, Nakamura-senko-futo, Kokubu and Sone).
In general, the seeds from the primary umbels showed the highest percentage in germination, the secondary umbels the second, and the tertiary umbels the lowest, respectively.
A consideration may be taken into account from the facts mentioned above that, at Kurume, the later the flowering time the more incident to summer rainy season the fruiting time is and the severer fungus diseases and physiological domages are.
3. In Kintoki variety native at Kurume, the yield of seed is smaller and the percentage of germination is lower than in the other native varieties in southern Japan. It is considered that one reason for these results depends on the time for flowering and fruiting later than that in the others.
4. The form of ramification of carrot is differents in each group of varieties. The oriental varieties show a standing habit of ramification with strong main shoot, large diameter of the primary umbel, and poor lateral shoots. On the contrary, the occidental varieties have a spreading habit with well developed lateral shoots and the secondary umbels large in diameter.
5. In the oriental varieties, the amount of seeds collected from the primary umbels showed a high proportion to the total yield. While, it was low in the occidental varieties.
6. In order to facilitate the selection and make good quality of seeds, it is desirable to collect the seeds from the primary and the secondary umbels, which are earlier in flowering and large in diameter, and to cut off the tertiary umbels.
7. The bolting percentage was investigated in some strains of Sanzun and Gosun varieties sown at different times (Aug. and Nov., 1954, Mar. 1955). There was a trend that the early bolting strains have a higher bolting rate.
8. For the purpose of surveying the difference of bolting among the individual plants within one variety, the seeds collected from different plants bolted at different periods were sown in Aug. and Nov., 1954. Then, the bolting time and bolting percentage were observed next spring. From these experiments it was recognized that the progenies from early bolted plants showed an earlier bolting and a higher percentage of bolting.

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This paper deals with two experiments carried out on the planting time and pre-sprouting treatment of seed pieces in Hokkaido.
The results obtained may be summarized as follows:
(a) The effect of planting time and pre-sprouting treatment on the growth and yield.
Six plots listed as follows were adopted for deter-mining the most desirable planting time of seed pieces in Hokkaido.
Plot A: Planted April 13, treated^*
Plot B: Planted April untreated^**
Plot C: Planted May 13, treated
Plot D: Planted May untreated
Plot E: Planted June 13, treated
Plot F: Planted June untreated
^* treated: Seed pieces were first planted in a hot-bed and transplanted to the field when the adventive bud appeared as a small knob.
^** untreated: Seed pieces were set in the field directly.
1. While the sprouting time was earlier in seed pieces planted early, the time required for sprouting was longer than that for seed pieces planted later.
2. In treated seed pieces the time for sprouting was shortened remarkably as compared with that for the untreated ones. As compared A with B, A spro-uted 18 days earlier; between C and D, C sprouted 13 days earlier; and between E and F, E sprouted 4 days earlier.
3. With respect to the yield, the earlier the sprouting took place, the larger was the yield. Taking the yield of plot D as 100, the yields of A, B, C, E and F became 129. 9, 109. 0, 119.8, 83.0 and 74. 1 respectively.
(b) The effect of the degree of pre-sprouting treatment on the yield and multiple formation of tuberous roots.
Four plots as listed below were adopted for a determination of the most desirable degree of pre-sprouting.
Plot A': Seed pieces were set in the field directly. (Control)
Plot B' Seed pieces were treated until the adventive bud was visible.
Plot C': Seed pieces were treated until the young stem and the young tuberous root were distinguishable.
Plot D': Seed pieces were treated to such an extent that both the stem and the tuberous root were approximately 3cm in length.
1. The seed pieces in treated plots sprouted con-siderably earlier than those in control plot. Among the seed pieces in treated plots, the earliness of sprout emergence had a tendency to occur proportion-ately to the degree of treatment. However, the differences between emergence times of each treated plot were not remarkable.
2. Nearly a quarter of the seed pieces in plots C' and D' failed to elongate their sprouts above the ground. This is due to sprout damage caused by sudden environmental change.
3. While pre-sprouting treatment raised the yield per plant, plot B' alone showed a higher yield based upon area.
4. Occasionally a single plant produces two or more tuberous roots. This phenomenon is designated by the authors as “multiple formation of tuberous roots”. From the standpoint of customary practice in the growing of yams, this is undesirable since it is responsible for more culls. It was further observed that more plants showed multiple formation in treated plots than in control plot.
From the results of the two experiments, it may be concluded that seed pieces should be planted early in May in Hokkaido and a slight pre-sprouting as in plot B' is recommendable, if the size of tuberous roots is not considered and only a greater yield is desired.

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1. In order to elucidate the mechanism of forma-tion of droppers in tulip, the authors investigated the effects of various cultural conditions on the dropper formation, using the small bulbs of William Pitt and Kansas.
2. In general, tulips nursed under conditions fa-vorable for the growth of the top and roots formed great number of droppers in deeper soil. Whereas, unfavorable conditions, the formation of droppers was less vigorous. For instance, with regard to the planting depth of seed bulbs, many more droppers were formed in the shallower plot than in the deep-er one (Table 1 and 2); in the test of soil moisture condition, more were found in wet soil than in dry soil (Table 4); more were found in the soil with lower ground water level than in the soil with higher one (Table 7); in the test of CO₂concentra-tion in the soil, more in the plot in which CO₂ gas was supplied to the soil than in the untreated plot (Table 9); with regard to soil reaction, more in neutral soil than in alkali or acidic soil (Table 14 and 15).
3. In the experiment of the effects of nutrient conditions, where the tulips were supplied with various quantities of three elements, the growth of the plants was found to differ by the plots, but there were no recognizable differences in the formation of droppers. This result can be ascribed to the fact that the droppers had already been formed before the leaf emergence stage, when the tulip really began to absorb the fertilizer.
4. In the study of effects of photoperiodism, the growth of the tulip was shown to differ according to the treatment, but as in the case cited above, it was hard to recognize any difference in the formtion of droppers, and it is presumed that this is mainly due to the fact that the droppers had already been formed before the leaf emergence stage, when the photoperiodic treatment was begun.
5. Considering the fact that the dropper began to be formed soon after the seed bulbs had been planted, it was generally concluded that although the cultural conditions may considerably affect the formtion of droppers in tulips, the innate characters of the seed bulbs themselves seemed to be a more important cause of it.

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The induced autotetraploid (2n=48) rose campions (Lychnis coronaria DESR.) are vigorous usually with thicker stems, thicker leaves and larger flowers than the ordinary diploids, although they grow -very slowly at the rosette young stage in winter and then begin to bloom later for several days than the latter. The petals are so large and thick, even though the size of flowers in a plant fluctuates in wide range, that they do not wilt so soon as the diploids when they are cut for decoration. By nature, rose campions begin to shoot the long stems with flowers firstly on the second early summer season after sowing. And it is ascertained clearly that their pollen and seed fertility are much influ-enced or changed by environmental factors, espe-cially “temperature”, during their flowering season. The ordinary diploid plants are easily capable of producing a plenty of fertile pollen and seeds in the condition of wide range of environmental tempera-tures. On the other hand, the autotetraploids prefer to the narrower, cooler temperature range for pro-ducing good pollen and fertile seeds than the former usually. For example, the former is possible to increase pollen and seed fertility sufficiently in the wide range of 20_??_28°C, signed with the maximum point of a day temperature at Utsunomiya; and the latter, on the contrary, necessitates the narrow range 23_??_26°C. The causes of such a peculiar phenomenon, of which the autotetraploids are distin-guished clearly from the diploids regard to reproduc-tive-physiological properties, will be explained generally by assumption of the presence of modifying minor genes for fertility. These genes are considered to be much sensible for environmental temperature but are latent or inactive in the ordinary di-ploids properly and, firstly when they are duplicated by chromosomal doubling, they will come into force to modify or tighten the optimum temperature range for increasing fertility, resulting the special adaptation of autotetraploids for the same climatic conditions as those of the regions where their an-cestral plants were grown up. Then the autotetra-ploid rose campion is regarded as one of the typical “cool-loving” species for fertility which are originated from the mild climatic temperate zone such as the South European districts.

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