356 MR. F. E. BEDDARD ON A NEW GREGARINE. [JunC 5, 



with individuals of the next stage ; this is characterized by its larger 

 size and rather more complicated structure. The general form of 

 the body is, however, the same. The drawing (p. 357) illustrates 

 this stage, as well as the encysted condition to be presently described. 

 The upper part of the figure represents an individual of the second 

 stage ; the lower part illustrates the encysted condition, in which 

 the whole Gregarine is enclosed by a cyst which is limited in the 

 figure to the lower process. 



In the second stage the body is limited externally by a clear mem- 

 brane of some thickness, which is probably the cuticle ; the coarse 

 granules which fill the interior of the parasite are sometimes restricted 

 to the globular part of the body, and are sometimes also found in 

 one or both of the slender processes. These differences are, however, 

 probably due to movements in the protoplasm of the living Gregarine, 

 which has been arrested at various intervals. The surface of the 

 two processes, and probably of the whole body, is covered with deli- 

 cate fibres, which generally run obliquely to the long axis of the 

 process, as is shown in the diagram (6). Careful focusing shows 

 these fibres to be quite superficial, and they are therefore probably 

 cuticular. During this stage, and also in the earlier stages, the 

 Gregarine multiplies by transverse fission — a process rare among the 

 Gregarinida '. 



The extremity of one of the processes becomes swollen and filled 

 with the granules of the entoplasm. This swelling increases in size 

 until it equals the body of the parent ; a process grows out from the 

 end opposite to that by which it is attached to the parent ; these two 

 then probably separate. 



In the third stage the body of the parasite is covered externally 

 with a remarkable cyst. Individuals in the encysted condition were 

 only met with in the substance of the vesiculse seminales of the 

 Perichceta. 



The structure of the cyst-membrane is illustrated in the lower half 

 of the drawing (c). It is of great thickness upon the one or two 

 processes into which the body of the Gregarine is prolonged ; it is, 

 however, much thinner upon the spherical region of the body. The 

 main mass of the cyst has a fibrous appearance, and imbedded in it 

 are numerous bodies which I cannot but regard as nuclei ; these 

 latter were evident in transverse sections, as well as in glycerine pre- 

 parations of the entire parasite. The presence of nuclei in the cyst 

 leads me to infer that the latter is not (at any rate entirely) formed 

 by the parasite ; the fibrous portion of the cyst, on the other hand, 

 looks as if it were an hypertrophied condition of the fibroid invest- 

 ment found in the free living parasites of the coelom described above 

 as stage 2. 



In some of the encysted parasites there was a single large nucleus 

 (a) ; in others a large number of smaller nuclei ; this condition is no 

 doubt preliminary to sporulation. Karyokinetic figures were observer' 

 in the dividing nuclei. 



^ Figured by Eusohhaupt (Jen. Zeitschr. 1885, Taf. xxii. fig. 13) in Mono- 

 cystis '^orrecta. 



