1. Using eight varieties of wheat, which are classified into three major groups of different earing habit (See Tabe 1), a number of transplantings of immature embryos into deyeloping seeds was carried out. An excised immature embryo of a foreign or its owh variety was inserted into the endosperm of a developing seed as depicted in Fig. 1., thus obtaining the matured viable seeds, each with two embryos, one of which is the proper and the other the transplanted. The author succeeded in raising a large number of such artificial twin seeds, eacb of which consists of two embryos of different varieta.1 nature or of the same. The pairs of plants were grown up from a number of such twin seeds, and their flowering responses were examirLed, making comparisons within each pair of sister plants as well as among the dlfferent pairs derived from various varietal combinations (See Table 3). 2. There can not be noticed any differences among the earing responses of the plants grown up from the transplanted embryos which, have the same genetic constitution but matured under different endospermous condition of the foreign varieties. In other words, those plants develop a quite similar number of leaves on their main stem before the ear-emergence, resuiting in neither promoting nor delaying the anthesis. The plants grown up from proper intact embryos of those twins show also quite similar situation in their earing behaviour, i. e., an additional transplanting of a foreign embryo having different earing habit into the developing seed does not exert any discernible influence on the earing character of the proper intact ernbryo.

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(1) In 1952 and 1955, we observed, with a view to find out the fundamental knowledge of breeding works, the manifestation of hybrid vigour between varieties and strains, of second inbred generation in our improvement work of Numbu cabbage and of spring' sowing cabbages. (2) F₁ plants could be distinguished from their parental varieties by their hybrid vigour and morphological characters, already on th. eir planting date (42 days after sowing), although the degree of hybrid vigour manifested was low at that time. (3) Hybrid vigou, r increased earliness of hybrids, though the effect was different more or less between the combinations of each varieties and strains. Numbu-strains and certain mid-season varieties showed greater hybrid vigour, when they partook one or both of parent of hybrid. The rate of acceleration of earliness was performed more by late variety combinations than by combinations of early varieties.

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One of the main difiiculties in the breeding of forest trees is the long time taken by trees to mature, in some cases as long as 100 years. Consequently it is impossible to, determine either the heritability of any economic character or the gerLetic correlation coeffi:cient between any two economic characters of forest trees at maturity. This paper intends to explore the possibility of finding, theoretically, techniques ofi selection useful for groups of plants of such longevity. Figure I in the tex. t is a diagralrk showing relations among a character of standing mother-tree (P₁) the same character of the offspring (P₃), to be observed in future, and a differeLt but more or less similar character of the offspring (P₂) in the nursery. E_i and H_i stand for the effect of i-th environment and that of i-th genotype on the i-th character Pi, respectively. rpaPJ is; the phenotypic correlation coefiicient between Pi and Pj while rHiHj is the genetic correlation coefficient between H_i and H_j. The letter hi in the figure is the square root of the. heritability value of the i-th character. For instance, we may assume that Pl be the, size of a mother tree, P₂ the mean height of young trees grown in the nursery from seeds collected from the mother tree, and P₃ the mean size of the offspring to be observed after 50 to 100 years. We can, then, hope to obtain the data for P₁ and P₂ only, and not that for P₃ in our time. From Figure 1, we can get the following formulae, assuming open-pollination of the trees.

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In the improvement of crop p. Iants by hybridization., it is desrrable that he parental varieties sh, ould differ from each other with regard to as many pairs of genes as possible when q, u:antitative characters are concerned. The genetic make-up of varieties closely related are likely to be very similar and that of remotely related ones likely to be dissimilar- Any survey or potential parental material should, therefore, take into account the relationship among the strains under consideraticn. Thus, in the case of autogamous plants, it is desirable for the breeder to know how varieties grown in his breeding nursery are related to each other .

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1. Studies were made on the crossability in reciprocal crosses between Abelmoschus escu, leletus and Abel. Manihot, and the characters and meiotic division in F₁ hybrids. 2. The set % of pods was higher in Abel. esculentusxAbel. Maleihot than in the reciprocal : cross. 3. The number of seeds per pod was larger in Abel. esculentusxAbel. Manihot than in the, reciprocal cross and these numbers were smaller respectively compared with those in the mother plants which were selfed. 4. The size of pods and seeds obtained in Abel. esculentusxAbel. Manihot vras smaller than those of the selfed mother while those obtained in the reciprocal cross were similar tothose of the selfed mother. 5. The appearance especially the colour of seed coat of F₁ seeds and their content obtained in Abel. esculentusxAbel. Manihot were similar with those in the selfed mother. Those of F₁ seeds obtained in reciprocal cross were mostly lustreless and empty comp. ared with those in the selfed mother.

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1. The crosscompatibility in the reciprocal crosses between "Nori-Asa, an amphidiploid crop raised between Abelmoschus esculentus and A. Manihot, and its parents, and also the characters and meiotic division in the sesquidiploid hybrids obtained among them were studied . 2. The set % of pods was almost the same between "Non Asa" x esculentus and "Nori-Asa" x Manihot, and those in the reciprocal crosses between the two plants of these two combinations were lower. 3. The number of seeds per pod was larger in "Nori-Asa" x esculeletus than in "Nori Asa" x Manihot, and those in the above two crosses were smaller than in the respective reciprocal crosses. 4. The size of F₁ seeds obtamed by Manthot x "Non Asa" was srmilar with that of the selfed mother, while those obtained by "Nori-Asa" x esculentus and "Nori-Asa" x Manihot were smaller than those of the selfed mother respectively. The F₁ seeds obtained by esculentus x "Nori Asa" were larger, compared with those of the selfed mother.

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In the previous paper the author reported that Edgeworthia papyrifera was allotetraploid and its two races. Shizuoka and K6chi, were of different genome constitution. He also reported the artificial induction of an octaploid of Shizuoka race by means of colchicine Itreatment. This octaploid plant proved to be self-incompatible like the original tetraploid. giving no seed on selfing. Crosses between the octaploid and the tetraploid Shizuoka race were successful only when the former was taken as the fenale parent, the resulting offsprings of which were confirmed to show the hexaploid number of chromosomes (2n = 54) in their root tip cell division. Abundant hexaploid offsprings were also obtained from the shoots of the octaploid left for open pollination. It is thus' clear that, being self-incompatible, ovules of the single octaploid plant left under natural conditions have no choice but to be fertilized by pollens of the tetraploid grown nearby. Microsporogenesis in the original tetraploid Shizuoka race was carried out quite normally, presenting 18 bivalents at MI. In the octaploid, more than half of the MI nuclear plates investigated displayed normal arrangement of 36II, but the remaining ones showed formation of 1-3 quadrivalents and rarely I trivalent. The division was, however, observed to proceed fairly regularly, showing almost equal assortment of daughter chromosomes at AI. In the hexaploids the microsporogenesis went on considerably irregularly. There were always found trivalents and randomly scattered univalents at MI, the former ranging in number from 4 to 10 and the latter from 4 to 7. The commonest configuration was 6III+ 15II + 6 I . In most cases the univalents lagged and remained near the equatorial region at AI, resulting in the formation of tiny, supernumerary microcyte nuclei.

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As a result of estrogen administration in White Leghorn chicken, it was recognized that the individual sensitivity have relation to her family's sensitivity, closely. Thereafter, the division of two strains about respective characteristic was attempted. In other words, the one was the sensitive strain, the other was the non-sensitive strain. The chicken acquired by means of sib-mating was offered in experiment. Diethylstilbestrol (solution of 50 mg. of stilbestrol in 20 cc of sesame oil) was injected intramuscularly to the chicken in 0.425 mg. daily dose. Estrogen injection was started on the 61 st day after hatching and continued for ten days. The sensitivity of chicken to estrogen was investigated from term which showed serum vitellin reaction. Results obtained here are briefly summarized as follows. ( 1 ) The sensitive group showed positive reaction in 67. 39, 75. 00% of all, but the non-sensitive group showed positive reaction in 28. 57, 29. 41% of all. ( 2 ) Significant positive correlation seems to be present between the term required in vitellin reaction and age at first egg. Namely, the coefficients of correlation were 0. 527 and 0. 619 in generation I and II, respectively. No significant correlation was present in intensity and clutch size. In conclusion, although it seems to be hazard to decide as the cases are few, it may be suggested that the difference of sensitivity in chicken due to the genetic control, and moreover it has relation to some of egg productive characters.

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The terminal bud of a tuber of "Konnyaku, "Amorphophallus Kanjac C. Koch, was previously cut with a knife to expose its growing point and 0.2-0.4 % colchicine solution was dropped on the cut surface of the tuber once a day for 2-3 days. Another method of treatment is soaking the terminal bud in the colchicine solution for 24 hours. 2.Out of 608 treated tubers from 3 varieties of Zairai, Bittya and Chinese only 3 were found to be tetraploid. Twenty six chromosomes were counted in the root tip cells of 2 x tubers and 52 chromosomes in those of 4 x tubers 3.Induced tetraploids are gigantic, as compared with diploids, in the size of stomatal cells, in the number of chloroplast in guard cells, and in other characters. 4. Tetraploid tubers produce thick and short stolevs which do not snap so easily as, those of dipoids.

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