184 I'HUJlAb H. BUYCE. 



latest conclusion (1899) regarding tlie strucLuru of the sea- 

 urcliin egg — namely, that the coutlilion of the cytoplasm 

 conCornis to Biitschli's description. It has the same physical 

 characters as an emulsion ; that is, there is a fluid framework 

 in which the microsomes are suspended, and the alveoli are 

 filled with a lluid of different physical characters. When 

 the alveoli are wholly destaiued all that is seen is the micro- 

 somic network, whereas when they are stained the alveoli 

 stand out as the yolk granules embedded in the cytoplasm. 

 Wilson shows, however, that the cytoplasm at certain periods 

 may have a fibrillar structure, but to this point I shall return 

 later. 



The changes which the nucleus undergoes during the 

 growth of the oocyte, until it becomes the fully developed 

 germinal vesicle, are very complicated and uncertain. 

 Many irregular figures suggest that the germinal vesicle 

 may undergo changes of shape. They may well be arte- 

 facts. 1 shall only refer to certain facts regarding the 

 cliemical reaction of the nucleus, which seem to be fully 

 vouched for in my preparations. It has been shown by 

 a number of observers that the staining reactions of the 

 nucleus vary at different times. At one time the chromatin 

 network will take the specific stains deeply, while at other 

 times it remains unstained (Ruckert, 1892). My experience 

 tends to support these statements, though one must 

 admit that very different effects are produced by different 

 degrees of coloration with iron ha^matoxylin. The effect 

 depends on the degree of extraction of the colour, but it is 

 quite certain that at certain stages of the nucleus the 

 network very readily parts with the black stain, and is left 

 as an irregular granular reticulum of a blue-grey colour, or 

 of a red tint, in preparations stained for contrast with rubin. 

 The nucleolus, on the other hand, is exceedingly tenacious of 

 the stain, and appears as an intensely black spot (fig. 2). 

 Again, at a stage I consider to be of later date, the network 

 shows a basis of delicate linin threads, with deeply stained 

 chrouiatiii ])articles arranged on the thread, giving it a very 



