CELL-ORGANS OF , SEA-URCHIN EGG 563 



Observations made in previous studies on hematopoiesis 

 invariably indicated the existence of wonderful gradation in 

 normal development and differentiation of cells, which seemed 

 to offer a great hindrance for a detailed study of reciprocal rela- 

 tions of cell organs. Since changes in normal cell development 

 could be incited by experiment, recourse to experimental method 

 was indicated. 



It is known, that the result of artificial stimulation of mature 

 sea urchin eggs by different chemical substances is a partheno- 

 genetic development of the egg. Besides the production of 

 normal larvae, many eggs develop under artificial stimulation 

 in a pathological way. A thorough study of parthenogenetic 

 development of the egg as well as a study of those eggs, of which 

 the development exhibited marked differences from the normal 

 conditions, might have thrown light upon the correlation of dif- 

 ferent cell organs. Therefore, besides series of normally ferti- 

 lized eggs, other series of eggs developed by artificial partheno- 

 genesis were collected. The artificial parthenogenesis was pro- 

 duced by the method of Professor Delage and the experiments 

 were carried out by Dr. de Beauchamp, the assistant of Professor 

 Delage, to whom it gives me much pleasure to express my 

 thanks. 



Among different fixatives Flemming and Zenker-Formol fluids 

 seemed to be most appropriate. As far as comparison of fixed 

 preparations with living material allows to judge, these fixatives 

 preserve all structures of the cytosome. Since both fixatives 

 gave similar results, I used chiefly Zenker-Formol, because of 

 the easier and better staining results following its use. The 

 eggs were imbedded in paraffin, while care was taken not to ex- 

 ceed 40 C. Different staining methods were applied, preferably 

 eosin-azur, saffranin and lichtgriin, and iron-haematoxylin. 



3. STRUCTURE OF THE EGG BEFORE AND AFTER MATURATION 



A cursory glance at figures 1 and 2, drawn from eggs before 

 and after maturation, may show the enormous changes, which 

 occur in the egg during maturation. Lack of adequate material 

 did not allow me to follow gradually these changes, therefore 



