Vol. XIII. 



June, igoy. 



No. i. 



BIOLOGICAL BULLETIN 



PATHOLOGICAL AMITOSIS IN THE FOOD-OVA 

 OF FASCIOLARIA. 1 



O. C. GLASER. 



In his paper entitled " Amitosis in the Embryo of Fasciolaria " 

 ('04), Professor H. L. Osborn has described the nuclear changes 

 occurring in the food-ova with which the embryos of Fasciolaria 

 tidipa gorge themselves at a certain stage of their development 

 ('05). Since the appearance of Child's paper ('07) will no doubt 

 stimulate fresh interest in direct nuclear divisions, I have decided 

 to publish this note on pathological amitosis, particularly as 

 Professor Osborn's description is unsatisfactory. Not only has 

 he conceived an erroneous idea of the structure of the nuclei in 



question, but he has failed to 

 point out the lesson which they 

 teach, for nuclear divisions which 

 have in common only the prop- 

 erty of being non-mitotic, are for 

 "•.;• that reason not necessarily com- 

 '•••: parable in other respects. 



The germinal vesicles of the 

 food-ova, placed excentrically in 

 the eggs, surrounded by a zone 

 of cytoplasm comparatively free 

 from yolk granules, are surpris- 

 ingly large. The only regions of 

 these vesicles that stain are the 

 enormous nucleoli in which the chromatic material is located be- 

 tween the bubbles of a fine non-staining froth. Outside of each 

 nucleolus, the nuclear material is composed of minute granules 

 1 Contributions from the Zoological Department, University of Michigan, No. 109. 



Fig. 1. Unfragmented germinal ves- 

 icle of food ovum. The large black 

 bodies represent yolk. 



