292 E. A. MINCHIN. 



fresh condition under low magnification^ and in fig. 20 I have 

 shown a single vesicle stained and mounted in Canada balsam, 

 with the coutanied Gregarine. The animal is egg-shaped or 

 nearly spherical, with two distinct nuclei, and no trace of any 

 septum visible, either in preparations in to to or in section 

 (fig. 21). 



The form under which I have found this animal agrees, 

 therefore, with the description given by Kolliker (1) . Schnei- 

 der (2) found it not only in the blood-vessels, but also in the 

 intestine and coelom. Mingazzini (5), however, seems to 

 consider the water-vascular system (" vasi acquiferi") as the 

 home of this Gregarine. He states that it was first found by 

 Kolliker in the water-vessels and intestine, which, however, is 

 not the case. Kolliker's words, " An den Darm- und Lungen- 

 gefassen der Holothuria,'^ leave no doubt as to his meaning. 

 At first I thought that Mingazzini must mean blood-vessels by 

 the words " vasi acquiferi,'' till I found that he terms blood- 

 vessels of Holothurians " vasi sanguigni" or '^ lacune connet- 

 tivali," in which he incidentally mentions the occurrence of 

 this form in the following words : — '' A peculiar property of 

 this species is the production of special cysts, which are 

 formed in the water-vessels (Wasi acquiferi') when it is pre- 

 sent. Nothing of like kind occurs when it is found in the 

 connective lacunes of the intestine" (p. 314). If by cysts 

 {^' cisti^^) the author means the stalked vesicles in which this 

 form is found, he is certainly in error in saying they do not 

 occur on the blood-vessels, which are, in fact, their chief seat, 

 as described by Kolliker and Schneider. For my part, I 

 am inclined to doubt the occurrence of this form in the water- 

 vascular system at all. Mingazzini further states that he has 

 found them free in the body-cavity. Those in the connective 

 lacunes of the intestine have more or less irregular contours. 

 With Schneider he describes the vesicles as detaching them- 

 selves and falling into the coelom when they are ripe for 

 sporification. Up to the commencement of sporification he 

 finds the animal divided in two by a septum. Schneider (2), 

 on the other hand, only found a septum iu some of the speci- 



