24 J. BllONTE GATENBY 



While this hcilps towards ii disposal of the view that the 

 chromosomes, at this period at least, are drawn upon to provide 

 material for the formation of secondary nuclei, it does not 

 dispose of the questions as to the nature and origin of the 

 nucleolus which buds off the secondary nuclei. 



It is possible to recognize several kinds of nucleolar activity 

 in various examples of oogenesis. 



definite nucleolus. 



Saccocirrus nucleolus 

 Apanteles nucleolus . 



nucleolar deutoplasm. 



definite nucleolus. 



secondary nuclei (associated 



with yolk-formation). 



^ , . 1 , (definite nucleolus. 



Grantia nucleolus . - \ . , i • /. , • i- ,x 



(mitochondria ( chromidia ). 



In certain other forms it is possible to recognize a process 

 of nucleolar extrusion early in oogenesis, but which appears 

 to lead to nothing (possibly in Patella). 



The belief held by some observers that nucleolar extrusion 

 may be looked upon as a process whereby the nucleus sends 

 chemical messengers into the cytoplasm inducing growth to 

 begin, is discountenanced, for Saccocirrus at least, by the 

 very apparent fact that nucleolar extrusion is prone to much 

 variation in the point of time and the rate that it takes place — 

 as shown by comparing the sizes of the eggs in PI. 3, fig. 23, 

 and PI. 4, figs. 29 and 33. The process is just beginning in 

 the first-mentioned figure, and has finished in the smaller 

 egg in the last-mentioned figure. 



(c) On the Supposed Chroma tinic Nature of 

 Extruded Nucleolar Material. 



If one fixes the testis or ovary of any animal in Zenker or 

 Petrunkewitsch fluid, and stains in Ehrhch's or Delafield's 

 haematoxylin and eosin or Biebrich's scarlet, it will be noted 

 that during the greater part of the development of the sperm 

 the chromatin stains blue, or basophil ; but there are certain 

 periods when what we can only assume to be true chromatin, 



