About the experiments on the effects of low temperature treatment with Japanese radish, race “minowase”. as the material, the following may be said:- 1. The existence of cotyledons during the low temperature exposure was favorable for bolting and the order of the bolting percentage was, decreasingly, seeds with two cotyledons>those with one cotyledon>those without cotyledon; which, however, was sometimes varied under certain conditions controlling the vegetative development after the plantation of the plant. 2. The presence of cotyledons during the growing period of the plant also brought about a rise in the bolting percentage. Generally speaking, the order was: materials with two cotyledons-with one-without. But also in this case disorder was sometimes seen under the influence of certain environmental conditions during the growth period of the plant. 3. The portion susceptible to the effect of low temperature treatment was seemingly the plumule itself, and not the cotyledon. 4. The cotyledon was supposed to play the role of a nutrition supplier in the course of vernalization. 5. The soaking of the hypocotyl, from which cotyledons were removed, in a 2% or 5% glucose solution during the period of low temperature treatment or the application of a 70% glucose solution to the cut surface of the hypocotyl left by the removed cotyledon, once prior to and again in the middle of the low temperature treatment, gave a somewhat good percentage of bolting. Yet it does not follow that the external supply of glucose is absolutely necessary for vernalization of cotyledonless seedlings. 6. A remarkable gap in the effect in relation to the duration of cold exposure, which causes bolting and flowering, was found between 14 days and 12 days. The same difference was also seen in the number of leaves up to the node of the primary flower stalk (primary pedicel). 7. The material used in these experiments was vernalized with a 7-day period of low temperature treatment at the shortest, and with the prolongation of the period increased in the intensity of vernalization. But in this parallelism there seemed to exist a limit, and the maximum, so far as observed, was the 27-dey period. 8. As to the number of leaf-primordia of the plumule of the seedling treated with low temperature, the material having cotyledons had more of them than the cotyledonless one. The writers are indebted to Ass. Prof. Y. Tajima of the Faculty of Agriculture, Kagoshima University, for his valuable suggestions in several courses of this study. The present work was supported in part by a grant out of the Fund for Scientific Research of the Ministry of Education.
In seedlings of Allium fistulosum and Allium odorum, chromosome fragmentations were often found, Their occurrence could be correlated to the developmental stages of seedlings. The breaks were almost chromosomal rather than chromatid. It is suggested that the factor or factors resulting from the specific metabolism in the early stage of seedlings rather than that from the aging of seeds may be responsible for the structural changes. Cytological effects of water extracts from aged and fresh seeds of welsh onion and soybean were described. It was ascertained that the water extract from embryos of aged soybean seeds gives weak radiomimetic action on mitosis. Fragmentation found in Allium fistulosum occurs predominately by breaking of the attachment fibre of the satellite in the nucleolar chromosomes. I wish to express my hearty thanks to Prof. T. Shimamura who has always given me good advices and encouragements.
1)Prospero kaj malprospero de amelogranoloj en la polenoj de Impatiens Balsamina estas observita sur kulturmedioj. 2) Fresaj polenoj povas kreski sur medio sen sukero. (Fig. 1) 3) Sur sensukera medio, amelogranoloj en polenoj multigas antau germado de tuboj kaj malmultigas responde al iliaj kreskado. (Fig. 3) 4) Ce la polenoj enlasitaj en humidcambreto, amelogranoloj malaperas iom post iom kaj preskall ne estas videblaj post 70 horoj. (Fig. 5) 5) Polenoj kiuj ne havas amelogranolojn kapablas sintezi ilin. Ekzemple: polenoj formigas ilin sur medioj kun glikozo, fruktozo au sukero. (Fig. 7) 6) Polenoj transmetitaj de medio kunn sukero 0% ai 20%, malaperigas amelogranolojn, sed kiam ili estas remetitaj al 0% ili denove formigas granolojn. La autoro komprenas la fenomenon de prospero kaj malprospero de amelogranoloj ke gi devenas de osmozreguligo en polenoj. (Fig. 6)
After several model experiments, we modified Schmidt and Thannhauser's method (Schmidt and Thannhauser, 1945) for the quantitative determination of nucleic acids and applied this modified method to plant cells. Procedure of the method is as follows: 1. Separation: A piece of plant tissues is weighed and ground for about 10 minutes in ca. 10 volumes of ice-cold 7% trichloroacetic acid. The suspension is centrifuged. The above treatment is repeated 3 times. Supernant contains acid soluble phosphorus substances. The residue is washed succesively with an ice-cold soln of 1% trichloroacetic acid, ice-cold water and ethanol. Then the residue is suspended in 30-40 volumes of mixture of ethanol and ether (3:1) and boiled for 5 minutes. Centrifuged. The residue is washed with ether followed by boiling for 30 minutes in 30-40 volumes of methanol-chloroform mixture (1:1). After centrifugation the residue is washed with ether. Phospholipids are extracted by the above treatment with organic solvents. The residue is dried and suspended in N-KOH (10ml per gram of fresh tissues) for 15 hours at 37°C. Centrifuged. The supernant is removed, 0.2 volumes of 6N-HCl and one volume of 5% trichloroacetic acid are added to one, volume of supernant, and kept in an ice-box for 30 minutes. White ppt is obtained. Then the suspension is centrifuged. Most of DNA is contained in ppt while phosphoproteids (in decomposed form), PNA (pentosenucleic acid) and a small amount of DNA are found in the supernant. The amount of DNA contained in the supernant is measured with Dische's method. PNA and inorganic P derived from phosphoproteids are separated by Delory's method (Delory, 1938) modified by us. 2. Decomposition: The result of our model experment showed that the decomposition of organic substances with perchloric acid gave better result than to ignite them over a microburner with H2SO4 or HNO3 (cf. King, 1932). Fig. 2. Absorption of developed color at different concentrations of phosphorus below 1.0γ/ml Fig. 3. Absorption of developed color at different concentrations of phosphorus between 60γ/ml and 100γ/ml 3. Reagent: a) 50% HNO3, b) 10% ammonium molybdate soln, c) ammonium vanadate soln (Dissolve 1.175g of ammonium metavaradate in 10ml conc. HNO3 and add 460ml dist. water). 4. Determination: For the quantitative determination of P, a method recommended by Fiske and Subbarow (1925) has frequently been employed by several investigators. But the result of our experiments showed that the color developed by this method was not stable and that a modified Barton's method (Barton, 1948) was preferable to the method of Fiske and Subbarow. In this phosphovanadomolybdate method (PVM method), the color developed is very stable and is hardly affected by the presence of silicates (Shigematsu, unpubl). Procedure: 0.6ml of reagent a) 1.0ml of reagent b) are added to 5ml of sample soln and followed by the addition of 3.4ml of reagent c). Keep 10 minutes at room temperature. Orange color developes. The transmittance of the color at different wavelengthes is shown in Fig. 1. In this figure it is seen that a maximum spread between the blank and the color developed is at 405mμ-410mμ. This wavelength is used for the spectrophotometric determination with a Beckman's spectrophotometer. The absorbance is proportional to the concentrations of P between 0.3γ/ml and 80γ/ml (Figs. 2 and 3).
In the present investigation, the tropism of pollen tubes of Lilium species was undertaken intending to see a relation, if any, between this tropism and the mechanism of penetration of pollen tubes from the stigma to the ovule in the fertilization of some higher plants. Pollen grains of Lilium longiflorum were spread around the pistil slices made from other flowers of the plant, or others, and the percentage of tropism was measured. The result of the present investigation shows that the pollen tubes are attracted to the pistils on the agar medium. Therefore it is highly probable to assume that pistils contain a factor which is responsible for the tropism of pollen tubes. This factor is contained in ovary tissues not including ovules, stigmas and styles (Table I), and diffuses into the agar medium (Table III, IV) and passes the collodion membrane (Table V). From these facts it is reasonable to assume that the factor is a chemical substance or substances of relatively small molecule, at least smaller than that of Congo Red. Since the pollen tubes do not show tropism to the pistils which have been steamed at 99°C for 10 minutes (Table II), it is concluded that the active substance is metastable to heat. Similer results were obtained in L. japonicum. Extraction of the active substance was tried but it was not able to separate with 50% ethyl alcohol or ethyl-ether.