132 Transactions of the Society. 



Summary. 



A. — Chromophility of the Cytoplasm of the Oocyte 



of Patella. 



1. Transition from an undifferentiated cell of the germinal 

 epithelium to an oocyte is marked by a change in the chromophility 

 of the cytoplasm from oxyphilia to basophilia. 



2. During the early stages of oogenesis, the cytoplasm remains 

 basophil. A change towards secondary oxyphilia occurs about the 

 time that the G-olgi elements have become scattered and the mito- 

 chondria are commencing active division. 



3. From this stage onwards, the cytoplasm becomes gradually 

 more oxyphil till definite secondary oxyphilia is attained. 



B. — Behaviour of the Nucleolus of the Oocyte of Patella. 



1. The nucleolus of the youngest oocytes resembles that of 

 certain of the somatic cells iu being an oxyphil body. 



2. During the early stages of growth before the commencement 

 of yolk formation, the oxyphil body extrudes portions of itself into 

 the cytoplasm. These fragments disintegrate or dissolve. 



3. At an early stage the oxyphil nucleolus becomes differen- 

 tiated into two parts, one of which remains oxyphil, while the other 

 begins to stain basophil. 



4. There is an extrusion of oxyphil substance during the 

 differentiation of the nucleolus, especially marked in that part 

 which is becoming basophil. 



5. Definite basophil and oxyphil parts of the nucleolus are 

 established, and in most oocytes they separate into distinct spherical 

 bodies. During the later stages of oogenesis, the oxyphil nucleolus 

 dwindles in size, and ultimately fragments into granules which are 

 extruded into the cytoplasm, while the basophil nvicleolus disinte- 

 grates and becomes distributed upon the linin network, mostly 

 in the form of little accumulations of basophil material around the 

 nodes of the reticulum. 



6. tt is suggested that the oxyphil substance extruded froix 

 the nucleus is related to yolk formation. The basophil substance 

 is tentatively assumed to stand in functional relationship to the 

 condensation of the spread out chromosomes into discrete chromo- 

 somes from the chromatinic network. This does not imply any 

 interference with the integral continuity of the chromosomes 

 throughout the germ cell cycle. 



