i9i 2] YAMANOUCHI—CUTLERIA 479 



Disregarding many points which may differ in particulars, the 

 case of Aglaozonia, in which bivalent chromosomes in seemingly 

 reduced number have originated by the folding back of sporophytic 

 chromosomes united end to end, will agree in essentials with obser- 

 vations made by different authors on various forms, for example, 

 by Farmer and Moore (13, 14), Schaffner (52), and Mother 

 (34) on Lilium, by Strasburger (58) on Galtonia, and by one 

 group of zoologists, such as von Rath (37) on Gryllotalpa, Ruckert 

 (41) on copepods, and Montgomery (31) on Peripatus. 



In general, while the method of forming bivalent chromosomes 

 by the end to end fusion of sporophytic chromosomes or meta- 

 syndese, as Gregoire (17) calls it, occurs in Fucus, Zanardinia, 

 Aglaozonia, and other forms, there is also another method by side 

 to side fusion, or parasyndese, in Polysiphonia (71), Nephrodium 

 (72), Osmunda (75), and various other forms, such as Lilium 



1), Allium (Berghs 2), Tril- 

 { Rosenberg 40). From these 



regoire 16, Berghs 2, Allen 

 m (Gregoire 16), and Drosera 



former 



in the formation of thread structures (leptotenes) from the resting 

 nucleus, and therefore in synapsis the two bent arms of a single 

 loop come into close association; and in the latter class, a duality 



is present at the time of the beginning of the thread structures 

 {leptotenes) , and the two independent members of the duality come 

 into contact during synapsis. In both classes, each of the two 

 elements of the bivalent chromosome is derived from a single 



chromosome, and the two elements separate in 



division 



seems 



types of arrangement of sporophytic chromosomes at synapsis 

 in plant cells. 



Some 



POLAR ORGANIZATION 



r organization of plar 



evidence of such polarity, the best 



known examples being Stypocaulon and Sphacelaria (61) 



form 



the 



resting nucleus of the apical cell. The centrosome is said 



• _ _____ _ m m % 



spindle, A similar 



mitosis 



