444 /. A. Gllrath and L. B. Bull: 



wall. The chromatin is spread throucrhout the nuclear space as 

 granular cords very irregularly anastomosing surrounding the 

 enlarged homogeneous nucleoli. 



In mature cysts the contents are formed by innumerable 

 fusiform germs, lOfx by 1.5/x, each of which contains a 

 definitely staining oval nucleus situated near one extremity, and 

 a small centrosome. Generally the nuclear extremity is blunter 

 than the other, which is abruptly narrowed. These germs are 

 arranged radially around a residual mass which gradually dis- 

 appears as they mature. 



In the earlier stages of the cysts observed by Chat ton there are 

 three distinct zones ; one internal condensed, a median zone of 

 clear cytoplasm, and an external thin zone, formed by the juxta- 

 position of the roots of the "" fringe." The contents consist of a 

 plasmodial mass in Avhich lie numerous glandular nuclei without 

 definite membrane. Tliese nuclei are grouped in divers manners 

 but not without order. Some are arranged as morula, some as 

 large spheres or ellipses, some in groups of two or three or 

 four, etc., but even isolated nuclei may be seen. As the cyst 

 matures the cytoplasmic masses contained in these nuclear 

 morula condense, while the interstitial cytoplasm rarities. The 

 groups of nuclei then form blastophores, of which all the nuclei 

 are regularly arranged at the surface under a tine membrane 

 or envelope. In all these blastophores simultaneously above each 

 nucleus a small cone of protoplasm appears. These cones increase 

 in size, and gradually form the fusiform germs. In the larger 

 masses all the nuclei do not form germs, a certain number re- 

 maining in the residual protoplasm, which itself as well as the 

 interstitial cytoplasm becomes completely absorbed during the 

 maturation of the cysts (Plate LXXXL, Figs. 19-20 c). It will 

 be seen from this precis of Chattoti's work how similar in many 

 respects is the early stage of development of the Gastrocystis to 

 that of the large cysts, particularly those of the kangaroo and 

 of the wombat which we have described, and even to some extent 

 of the wallaby cyst. 



Chatton discusses the enlargement of the epithelial cells as a 

 result of the invasion by the parasite. He admits that because 

 of its dimensions, its structure, and especially the fringe-like 

 l)eripheral arrangement it does not appear at first sight a modi- 



