TOXOPNEUS.TES VAKIKi.ATl - 



over <>r under tin- V--haped chromosomes, and this holds f.-r 

 all -imilar 1'iL'iirr-. >p< ial care was of course taken to keep tin 

 'i'.n !" the Ion- rod-shaped and the \*-shaped chromosome^ 

 iiratcly as possible. 



I- i. shows daughter plates of a late anaphase where th< 



arc tlin-c V--haped (hi :iies \vith more nearly parallel arm>. 



T\\o ot the-e t hronio-<,ni( - are very close together, one partly 



mother in each plate. Fig. 3 also shows in a aiv 



three \--haped < hn.mo-. ,me- in early anaphase. One pair of 



the-e ehronio-ome- apjM-.ir- -mailer than the two others, but 



in evui'imiu othei I I '1 no regularity in the apparent 



the ilin-e pair-, Sometimes all three pairs vary a little, 



sometime- ti tly the same si/e, sometimes 



onU i lie member- ..! <>ne pair \ apparent size. This dit- 



ma\ IM <hie to dii- ictimi or to an original 



diltei.iK. in length of the i hroino-oiiies. As Balt/er's ('090, 



urements of the hook-^hajn-d chromosomes show, 



i In length of ch<mosomes of a certain t\|H- is (jiiite variable; 



it ma\ \ar\ Irom <>-^ ijo mm. rr is no n-st-inblance 



ho\\i \ ( i to the t omlitioii-N in :is in res|X.'Cl to the 



thinl jiair <f hook--ha|M-<l ehromo-onn-, \\hith always is coiisid- 



1\ -mailer than t he oiht-r two. 



< IIM- of the three Y-sha|>ed chromosomes is probably a hetero- 

 . hronii-onie. as Ralt/er assumes to account for the conditions 

 loimd in -ntrotus and Echinus. Studies in orogenesis 



and -|>eriiiat"^eii( -i- u-.nld be necessar\- to obtain evidence 

 li T ' 'i a^ain-t tin -tion ma<le. 



\- it i- dilfu uh to ic. tint the total number of chromosomes in 

 a lateial \ie\\ o| the daughter plates I counted the number in 

 I ic ilar \ie\\- \\here tort unateU' the X'-shajK-d chromosomes sho\\ 

 \er\ i learly. 



l-i. ! presents two succeeding sections through 



t\\o anapha-e daughter j)lates; the \"-shaped chromosome- are 

 the t\\o double ones, finished in solid black. The number ot 

 fhromo-oine- in earh j'late is 36. l ; i^. ~ shows a plar \ ieu with 

 thn. \ -hajted cliromo-<mes; here also the number i- 36. 



I (..tinted 14 anaphase plates from the pole, \\ith a clear 

 arrangement of chromosomes, and found the average number 



