63 The Chromatin in the Development of Hybrids 



PLATE III. 



Fig. 19. Anaphase of the third cleavage of a Menidia hybrid. In the 

 upper half of the spindle the two kinds are clearly bilaterally distributed. 

 J' Fundulus. $ Menidia. 



Fig. 20. Early anaphase of the fourth cleavage of a Menidia hybrid. 

 The two kinds of chromosomes are evidently mingled. (^ Fundulus. 

 5 Menidia. 



Fig. 21. Chromosomes from a fourth cleavage spindle of a Fundulus 

 hybrid. The cell w^as in anaphase. The chromosomes of the drawing 

 are such of one end of a spindle in a single section as could be distinctly 

 made out. They are drawn by only the partial aid of the camera. Each 

 chromosome is faithfully reproduced so far as its form and size are con- 

 cerned but its position with reference to its neighbor is not in every 

 instance retained in the drawing, c? Menidia. $ Fundulus. 



Fig. 22. Anaphase of cell from middle cleavage of a Menidia hybrid. 

 The two kinds of chromosomes are mingled. The short ones, as a whole, 

 are nearer the i^ole than the long ones, so that they form a band extending 

 across the spindle. J' Fundulus. 5 Menidia. 



Fig. 23. Telophase of the third cleavage of a Menidia hybrid. Only 

 one-half of the spindle is shown. Of the two groups of vesicles the smaller 

 ones, nearer the poles, are probably from the short chromosomes. The 

 group of larger vesicles is composed for the most part of the long chromo- 

 somes not yet so far along in their metamorphosis. ^ Fundulus. 5 

 Menidia. 



Fig. 24. Late anaphase of a cell from middle cleavage of a normal Men- 

 idia notata. Only the small type of chromosomes are present. Compare 

 with corresponding stages in Figures 22, 26 and 32. 



Fig. 25. Early anaphase of cell from early cleavage of a normal Fun- 

 dulus heteroclitus egg. Only the long chromosomes are present. 



Fig. 26. Late anaphase of a cell from later cleavage of a normal Fun- 

 dulus heteroclitus egg. Only the long- type of chromosomes are present. 

 Compare with corresponding stages shown in Figures 22, 24 and 33. 



Fig. 27. Cells from middle cleavage of a Menidia hybrid. They show 

 the double nuclei in these cells. 



Fig. 28 is omitted on purpose. 



