1) In some cases, the flowering stimulus can be transmitted across a graft union. It was possible to stimulate Xanthium to flower initiation under long day conditions by graft-uniting it to photoinduced long day plants such as Erigeronannuus, Rudbeckia bicolor and Centaurea Cyanus. 2) Often abnormal flowers and fruits were produced on the receptor plants. The fruits were smaller than those produced on normal plants in the field and various abnormalities in structure were observed. 3) Xanthium cannot becaused to initiate flowering by grafting with Tagetespatula, Aster Savatieri, Coreopsis lanceolata and Crysanthemum coronarium var. spatiosum
(Reduction divisions in hybrids between N. suaveolens and three other species.) Reciprocal crosses between N. suaveolens (n=16) and four other species, N. gossei (n=18), N. alata (n=9), N. longiflora (n=10) and N. plumbaginifolia (n=10), were carried out. The reciprocal crosses between N. suaveolens and N. gossei gave always many germinating seeds, while the other six crosses did not produce any seeds, with the exception of N. suaveolens×N. longiflora and N. suaveolens×N. plumbaginifolia. In the meiosis of the PMC's of the hybrid N. suaveolens×N, gossei, the chromosome configurations most frequently found were of the following three types, 2III+14II, 1III+15II+1I and 16II+2I. Besides, several polyvalents were occasionally observed, and many chromosome bridges were seen at first anaphase. This suggests the presence of some inversions or translocations between the chromosomes of N. suaveolens and those of N. gossei. The study of meiosis in the PMC's of the two hybrids, N. suaveolens×N. longiflora and N. suaveolens×N. plumbaginifolia, agreed very well with Kostoff's observations, the number of bivalents in the former being 0-3 and in the latter 0-4. Since the chromosome configuration 1II+24I was mostly observed in the above two hybrids, it seems that one pair of chromosomes with long homologous parts in common is present among the chromosomes of N, suaveolens and N. longiftora or N, plumbaginifolia. In the hybrid N, suaveolens×N. longiflora, cells of the tapetum tissue were strikingly enlarged at an early stage of meiosis, and all PMC's, from unknown causes, almost always degenerated and disintegrated before the end of the reduction division.
The reduction of 2, 3, 5-triphenyltetrazolium chloride (TTC) by embryo slices of Phaseolus vulgaris was studied. Excised radicle and hypocotyl were sliced longitudinally with a razor blade and incubated in reaction mixtures containing 10-2% TTC, 10-2M sodium succinate and 0, 088M phosphate buffer (pH6, 8) at 28°C in dark. Then the appearence of red colouring was observed in various time intervals. Under these conditions, the colouring, indicating the reduction of TTC to triphenyl formazan, was appeared at the procambial region, and was facilitated by addition of sodium succinate (Table 1). Effects of temperature and some inhibitors were studied under the existence of succinate. (1)The reducing activity of the tissues was completely damaged by pretreatment at 52°C for 30min. (Table 2, 3), and influenced by the incubation temperature (Table 4). (2) The reduction was also completely inactivated by monoiodoacetic acid at the concentration of 10-3M (Table 5, 6). (3) Malonate, known as a specific and competitive inhibitor of succinic dehydrogenase, inhibited the reduction only slightly when added in the reaction mixture (Table 7, 8). When the slices, however, were pretreated with a 10-2M malonate solution for 37min, the inhibition increased intensively (Table 9). (4) The reduction was prevented completely by pretreatment with 10-1M lead nitrate solution (Table 10). When these slices were washed with a dilute solution of ammonium sulphide after the treatment, their procambial regions became stained brown just at the corresponding places formerly stained red. This brown precipitate was proved as lead sulphide, and these facts suggest that the inactivation by lead salt may be due to the combination between lead ions and enzyme protein (probably succinic dehydrogenase). (5) When the phosphate buffer was replaced with acetate buffer, the reaction was completely inhibited (Table 11). (6) Potassium cyanide inhibited the reduction at the concentration of 10-3M (Table 12, 13). This inhibition may be due to the inactivation of succinic dehydrogenase as was pointed out by Tsou. Standing on the basis of these results it was concluded that the site of staining, i.e. the procambial region, was that of succinic dehydrogenase, although it was not confirmed with certainty yet what was the direct carrier of hydrogen atom to TTC.