John P. Munson 315 



the larger ones, the hyaline karyolymph becomes turbid by the deposit 

 of chromophilous granules. This renders the nucleus more conspicuous, 

 owing to its increased size, and its greater staining capacity. The cyto- 

 plasm of these oogonia is rather hyaline, and does not stain at all deeply 

 in nuclear stains. The cytoreticulum can, however, be seen. 



The Centrosome. 

 In the immediate neighborhood of the nucleus, in the cytoplasm, there 

 is a true centrosome. The amount of cytoplasm is not great, but at one 

 pole of the nucleus there is more of it than elsewhere. The centrosome 

 can here be seen in the form of a tiny body close to the nucleus. It may be 

 more or less conspicuous according to the amount of archoplasm sur- 

 rounding it. The archoplasm is apparently not always present. The 

 centrosome itself, i. e., the central granule, is an exceedingly minute 

 body which comes into view only on focusing, when it often stands out 

 sharp and clear in the center of what seems to be a clear globule, sur- 

 rounded by a ring of microsomes. In fact, I have seen this clear globule 

 often when I have been unable to make out the central granule — a fact 

 that may be due to defective focusing. Prom the circle of microsomes 

 surrounding the clear globule, the cytoreticulum radiates, usually becom- 

 ing crowded along the sides of the nucleus and forming a thin layer 

 investing the nucleus. My experience with these germ-cells has made 

 me very suspicious about all negative evidence concerning the centrosome. 

 That such a tiny granule is not always visible is not strange, when it is 

 noticed how the cytoplasm varies as regards its density and transparency, 

 not only in variously preserved material, but in the living state as well. 

 As is plain from the later history of the centrosome, to be related pres- 

 ently, the presence or absence of the central granule may or may not 

 be important. What is of greater importance, perhaps, than the central 

 granule is the circle of microsomes surrounding it, and from which the 

 fibrils of the sphere seem to radiate. To say that this central granule 

 is homologous to or identical with the ordinary cytomicrosome does not 

 signify much either one way or another, so long as the radial system of 

 fibrils in its immediate vicinity can be shown not only to exist at this 

 early stage, but to persist throughout subsequent stages of the growing 

 Qgg. The extreme tenuity, also, of the radial fibers of the sphere, especi- 

 ally in the resting condition of the astral system, often makes it seem 

 more surprising that they can be seen at all' than that they should at times 

 become obscured by granules or otherwise become invisible, be it due to 

 reagents used in preparing the tissue or to varying states of the fibers. 

 The fact seems to be that the fibers of the cytoreticulum have the power of 



