PLATE 1 



EXPLANATION OF FIGURES 



4.11 figures are drawn to a magnification of 1500 diameters. 



1 A, B, C, D. Toxopneustes 9 X Hipponoe cf. Normal sea water. Three 

 longitudinal sections of anaphase of first division. Vs shown in B were lying 

 beneath Vs in ^. Chromosomes.* upper plate, 34; lower, 34. 



2 A, B, C. To.xopneustes 9 X Hipponoec?. Normal sea water. Three 

 longitudinal sections of anaphase of first division; chromosomes : 30 and 31. 



3 A, B, C. Same; chromosomes: 34 and 32. 



4 A, B. Same; three sections combined in two; chromosomes: 30 and 31. 



5 A, B, C. Same; chromosomes: 33 and 33. 



6 Same; early anaphase; part of one section. 



7 A, B. Same; three sections combined in two; chromosomes : 33 and 34. 



8 A, B. Same; three sections combined in two; chromosomes: 38 (?) and 

 35 (?). Some of chromosomes probably sectioned. 



9 A, B. Same; sea water and acetic acid; chromosomes 28 and 29; those at 

 center not counted. 



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