OBSEEVATIONS ON THE GEEGAEINES OF HOLOTHUEIANS. 279 



Observations on the Gregarines of Holothurians. 

 By 



E. A. Mincliiu, B.A., 



Assistant to the Linacre Professor of Human and Comparative Anatomy, 

 Oxford. 



With Plates XXVII & XXVIII. 



Our first knowledge of the Gregarines of Holothurians 

 dates back to Kolliker (1), who in 1858 described " vesicles 

 for the most part stalked^ with a distinct envelope, and 

 granular, dark, fat-like contents, which invariably contained 

 two germinal vesicle-like bodies, each with a large, finely- 

 granulated, germinal spot-like structure. Some of these 

 structures were sessile on the (blood-) vessels (of the intestine 

 and respiratory trees), and were covered by ciliated peritoneal 

 epithelium, while the stalked ones were apparently always 

 naked." The author was at a loss to understand the signifi- 

 cance of these structures, and " simply recommends them to 

 later observers.^' 



In the following year Anton Schneider (2) identified these 

 bodies as Gregarines, and termed them Gregarina hoio- 

 thurise. He found them in the intestine, blood-vessels, and 

 free in the body-cavity, and figures a specimen from the blood- 

 vessels, where by continually increased bulging out of the 

 wall they form the stalked vesicles of Kolliker. In all those 

 from the blood-vessels he observed two nuclei, as also in many 

 from the body-cavity. In the latter by slight pressure of the 

 cover-glass he observed a furrow dividing the contents into 

 two halves, each with a nucleus ; in the former he could not 

 observe this furrow. In contradiction to Kolliker he found 



