CHROMOSOME STUDIES 223 



2a. Y-shaped chromoso7nes in plant-cell mitoses, not including 

 prophase and metaphase of the first maturation division. True 

 V-shaped chromosomes have been described in LiHum, AUium, 

 TrilHum, Helleborus and Podophyllum. In Lilium they have 

 been shown by Gregoire ('99, '10), Strasburger ('00), and 

 Mottier ('03, figs. 6, 8, IG, 41). Only in figures 16 and 41 does 

 Mottier present any indication of transverse segmentation. 

 Gregoire's ('99) figures show V's, but, with the exception of 196, 

 c, and d and one or two chromsomes in figures 22 and 23, it is 

 impossible to distinguish between the true V's and his V-simples. 

 Mottier describes these chromosomes as straight rods, bent 

 rods, and U's. His figures indicate that for the genus Lilium 

 probably a large number of rods is characteristic. Bonnevie 

 ('11, figs. 12, 13) finds in AUium both V- and rod-shaped chromo- 

 somes (figs. 55-60). Like Gregoire, she has failed to distinguish 

 between true V's and V-simples. The former show a split along 

 each arm of the V in the anaphase. Mottier found similarly 

 shaped chromosomes in Podophyllum (figs. 22, 23), in Trades- 

 cantia (fig. 32), and in Helleborus (see Gregoire, '09, fig. 19). 

 As to whether any of the V's in the genera described would on 

 re-examination show the segmentation at the apices, I cannot 

 tell, except in the case of Podophyllum, where in root-tips cells 

 I have found segmentation similar to that shown in Chorthippus. 



In TriUium, Gregoire et Wygaerts ('04) have observed three 

 cases of segmentation, of which they say, 



Nous observons tres souvent dans les chromosomes-filles une ou 

 plusieurs fentes trans versales, tres precises, comme taillees au couteau, 

 Fig. 20. Elles se correspondent parfaitement d'un segment-soeur k 

 I'autre, Fig. 20. II est certain qu'il ne s'agit pas la d'une fente com- 

 plete; le chromosome en effet ne se disloque jamais; mais nous n'entre- 

 voyous pas d'explication de ce ph^nomene, que nous ne faisons que 

 signaler. 



This transverse segmentation corresponds with what I have 

 found in Chorthippus. Since at least five of the seven pairs of 

 chromosomes in this genus are V's, as figured by Atkinson ('99) 

 and by Gregoire ('09); since many of these chromosomes have 

 unequal arms, almost identical to my no. 7-1 1's or 8-10's in 



