126 Transactions of the Society. 



cytoplasm colours differently according to the stage of develop- 

 ment of the oocytes. With Mann's methyl l^liie eosin the nuclei 

 of typical somatic cells stain blue and their cytoplasm purple, 

 while witli hematoxylin and eosin used according to Scott's 

 method the nuclei are purple and cytoplasm red. The undifferen- 

 tiated cells of the germinal epithelium appear to stain in the same 

 way. However, when such cells begin to develop into oocytes, a 

 change takes place both in their nuclei and cytoplasm. The latter 

 begins to stain basophil (that is, with methyl blue eosin it stains 

 blue, with hsematoxylin and eosin purple). During growth of the 

 oocyte, by the time that yolk spheres are sparsely scattered through- 

 out the cytoplasm its chromophility undergoes a further change. 

 The bhie or purple colour very gradually gives place to red again. 

 This change in staining properties occurs at about the same 

 time as the scattered mitochondrial granules {11) commence active 

 division. In- the full-grown oocyte the cytoplasm stains similarly 

 to that of the undifferentiated epithelial cells. 



There is therefore, in the process of development of the egg 

 from a cell of the germinal epithelium, a change from primary 

 oxyphilia to basophilia, followed by a state of secondary oxyphilia 

 in the mature oocyte. 



The Nucleola-K Phenomena .during the Oogenesis 



OF Patella. 



The nucleolar phenomena were studied in material fixed in 

 Bouin (with acetic) or corrosive acetic, and stained with Mann's 

 methyl blue. eosin, or hsematoxylin and eosin, or lichtgriin and 

 safranin. 



The nucleolus of a typical somatic cell stains oxyphil, as is 

 shown in Fig. 1, Plate III, which represents connective tissue 

 cells from the digestive gland. The nucleus of the youngest 

 oocyte has also a small oxyphil nucleolus. In Fig. 2 is shown a 

 young oocyte growing up from a trabecula of the ovary amongst 

 three yolk cells. As such an oocyte as this grows the nucleolus 

 increases considerably in size until it comes to occupy a large area 

 within the nucleus. During such early growth phases there is a 

 considerable extrusion of the oxyphil substance into the cytoplasm. 



In Figs. 2 and 3 are shown the large oxyphil nucleoli (NL), 

 and in the cytoplasm the oxyphil substance (NE) derived from 

 them". This extruded substance appears to dissolve slowly in the 

 cytoplasm, as different fragments show various intensities of coloura- 

 tion ; some are as red as the nucleolus itself, while others are 

 purple in colour, due it would seem to intermingling with the 

 ground cytoplasm, which stains blue. 



It will be observed from the figures shown in Plate III. that 



