Abstract
The reduction thvision in PMC's was studied in 4 hybrids between N. paleiculata and 4 other species Of section Alatae, namely N. paniculata x N, alata, N. paniculata X N. Ialegsdorffii, N. paleiculata X N. plumbaginifolia and N. paniculata x N. Iolegiflora. 1) F1 of N. paleiculata (n=12) x N. alata(n=9). At MI of PMC's of this hybrid, the number of bivalents ranged from 0 to 6, with the mode at 3. The frequency of PMC's with 4 and 2 bivalents followed that of PMC's with 3 bivalents. PMC's with I and 5 bivalents were occasionally found but those with 6 bivalents or without bivalents were very rare. In the same hybrid, KOSTOFF (1943) found that the number of bivalents ranged from 2 to 7 and observed occasionally a few trivalents. His obeservation of trivalents is doubtful because the trivalentlike chromosomes in my preparation were hetero-morphic bivalents. Otherwise KOSTOFF'S results generally agree with mi.ne. 2) F1 of N. paniculata (n=12) X N. Iaeegsdorffii (n=9) . At MI of PMC's of this hybrid, the bivalent range was from 0 to 4 with the mode at 1 and 2. The frequency of PMC's with O bivalents followed that of PMC's with Ilor 2 bivalents. PMC's with 3 bivalents were occasionally fcund but those with 4 bivalents were very rare. In the same hybrid, GOODSPEED(1954) found that the number of bivalents ranged from O to 4, with the mode at 2. His results agree with mine. According to KOSTOFF'S description (1943), he and also DREMLUG observed in the same hybrid that the number of bivalents ranged from 0 to 7 and some trivalents were present. The difference bctween the results observed by GOODSPEED and also myself and those of KOSTOFF and DREMLUG is too large to be attributed to different strains used by the authors. 3) F1 of N. paniculata (n=12) X N. plulecbagilei-folia (n=10) . So far as I know, no investigation of this hybrid has been published. At the MI of PMC's, the bivalent range was from 0 to 3, with the mode at O. Accordingly N. paleiculata is assumed to be less related to N. plueebagileifolia than to N. alata and N. Iaecgsdorffii. 4) F1 of N, paleiculata(n=12) X N. Iongiflora (n=1O) . No findings on this hybrid have been reported till now, so far as I know. At MI of the PMC's of this hybrid, the number of bivalents ranged from O to 2, with the mode at O. N. Iongiflora is very closely related to N. plumbagilcifolia, and the chromosome pairing in hybrids N. paeeiculata X N. Ioleiflora and N. palciculata x N, plumbagilcifolia was similar. From the results of the chromosome pairing in the four hybrids mentioned above, it is assumed that N. paniculata is not related to the above four species belonging to section Alatae.
