I -I, EDITH PINXKY. 



appearance predominates. Fig. 3/< is a typical \ lew. The lai i 

 pair i- racily identified but one can lie MIIV of only one Miialler \'. 

 Its mate may be the Mnal! thick element, r, lying iu-\t to on< 

 tin- larger YV In Fig>. II, 12, 13, 15. 1 6 and 17 some of the 

 Vs from several otlu-r spindles are shown. Owing to individual 

 differences in tin- eggs it would hi- impossible to identify the 

 large or the small pair as such unless the other pair could be 

 distinguished. 



Miss Heffner did not observe any constant difference in size 

 or behavior which might mark the unpaired Y in Toxopneustes. 

 The size relation of the Hipponoe Y's is very plain in early ana- 

 phases as I have already explained. 



I ha\e examined sections of Toxopneustes eggs made from the 

 same material that Miss Heffner used and am able to confirm 

 her observations upon the appearance and behavior of the Y- 

 shaped elements. The long rods are also very conspicuous (Figs. 

 19, 20 and 21). A peculiarity, presumably of the egg, calls for 

 different degrees of differentiation in staining early and late 

 anaphases. I could not find on the slides that I examined early 

 anaphases where the condition of things could be made out satis- 

 factorily although there were plenty of later stages which were 

 as clear as one could wish. In these I have observed and give 

 figures (20 and 21) which show a difference in the size of the Vs 

 which would indicate that the unpaired V is the smallest, yet I 

 hcMtate to accept this alone as evidence that such is the case. 

 Fig. 21 shows two large and one small V in the upper group. One 

 large V is missing from the lower group. The indications were 

 that it had been displaced by the knife in sectioning. Miss 

 Ilellner's I'gs. la, and 3, a and /;, depict two spindles in early 

 anaphase. From these figures and from what I find in Hipponoe 

 \\here Mich stages are comparatively abundant and convincing 

 I feel j u Mi lied in concluding that the unpaired Y or heterochromo- 

 some in Toxopneustes is the smallest V of the complex. 



In Figs. 3, 9 and 10 is shown the- third type of echinodeim 

 chroni"~<ime, the hook. It corropmids in all aspects to t he- 

 hook described \>\ Baltzer. In !Iip/>onoc it occurs Miigly and 

 is not present in all of the c.uv^. ( )f tuent v-nine ci^s in which 

 its presence or absence' could be determined with certainly seven- 



