782 FRANK E. BEDDARb, 



belong to some form of Gregarine. They were in many cases plainly 

 distiDguishable from the cysts of the common Monocystis lumhrici by 

 the fact that one end of the cyst was prolongcd (see pl. XXII, fi». 1 c) 

 into a stalk of attachment ; in some cases two cysts were attached by a 

 Single stalk (pl. XXII, fig. 1 c). Moreover the cyst is very much thicker 

 in the form under consideration ihan in any of the species that have 

 hitherto been described as occurring in the earthworm. 



My notes upon this Gregarine by no means form a complete 

 account of its life-history. I have however been able to observe three 

 stages, which are not without interest. 



In figs. 1, 2 are depicted a number of the encysted individuals; 

 the figure illustrates the very remarkable variations in the form of 

 these cysts. But of a very large number which I examined only two 

 or three had an unbroken rounded or oval contour. In every case 

 when the cyst had this regulär form it contained (fig. 2) apparently 

 two Gregarines. The individuals were not completely separated from 

 each other by a septum ; there were only indications of such a septum 

 at the periphery; centrally it was even difficult to distinguish 

 the boundary between the two individuals. Such cysts, which were 

 by no means common, are not unlike the double cysts of Porospora 

 giyaniea figured by van Beneden. In by far the greater number 

 of cases the cysts were fusiform or stalked ; sometimes (fig. 1 h) the 

 stalk was exceedingly short; in other cases (fig. 1 c) it was very 

 much longer than the cyst. Frequently each end of the cyst was 

 prolonged into a short stalk (fig. 1 d), or one stalk might be very much 

 longer than the other (fig. 1 e). The most characteristic form of the 

 cysts is illustrated in fig. 1 c , here two cysts are seen to be connected 

 by the extremity of their stalk; when two or even more cysts were 

 thus connected, there were considerable variations in the length of 

 the stalk. 



1) Membraues of Cyst. 



The most remarkable feature about these cysts is the structure 

 of the cyst itself, that is of the outer membrane which encloses the 

 parasite. 



The cyst as in most of the Septata (Lankester, 1) is made up 

 of two layers, The inner layer is very fine and shows no structure 

 (fig. 3). The outer layer forms a very complicated membrane which 

 is best seen in transverse sections (fig. 4). I have already referred 

 to the stalked Gregarine cysts; in these the outer membrane is very 



