EXPLANATION OF THE PLATES. 



Plate I. 



1. An egg before the fading of the germinal vesicle. There are one large 

 and nine small plasmosomes, each associated with a chromatin mass. Total 

 preparation. X 333. 



2. Nucleus of a hlastomere at the two-cell stage. X 866. 



3. The same at a little later stage ; the nuclear membrane has been 

 dissolved at the poles. Change in the chemical nature of the nuclear 

 fluid. X 806. 



4. Early prophase of the first cleavage mitosis, showing the darker portion 

 of the rays in the nuclear region. X 800. 



5. One large and two small plasmosomes with two chromatin masses. 

 Auerbach's stain. X 2000. 



G. Large plasmosome almost dissolved ; disc-shaped precipitation granules 

 are seen on the left hand side, x 800. 



7. Basket-like residual mass of a larger plasmosome. X 860. 



8. Four large and one small plasmosome. Near one of the large plasmo- 

 somes is a thread-like coagulum. X 800. 



9. Small plasmosome with a chromatin mass. Reticular coagulation of 

 the nuclear fluid, x 2000. 



10. Small plasmosome with a chromatin mass ; the former has noticeably 

 decreased in size, x 806. 



11. Small plasmosome consisting of two portions like the large one. 

 X 866. 



12. Larger plasmosome which has become hollow. One of the chromatin 

 masses is embedded in it. x 2000. 



13. A portion of the germinal vesicle of a CaCL-egg containing thread- 

 like chromatin masses. X 866. 



14. Prophase of the first maturation mitosis, showing four (or three) 

 extra chromatin masses. Two long rays are reaching a chromatin mass. 

 Combination of eight sections. X 806. 



15. Equatorial plate of the first maturation mitosis seen en face con- 

 sisting of 18 bivalent chromosomes. X 866. 



10. The same consisting of 11) bivalent chromosomes. X 800. 



