3^8 Mr. T. Bentliam on some 



its larger stages lying alongside tlie nucleus of tlie liost-cell. 

 Tlie smaller tornis were always definitely rounded in slia}X', 

 resembled 2'Iasi>iO(/ia, and never more tlian two -were to be 

 seen in a single erythrocyte (see Pi. XVII. tig. 1, 5 & 6). The 

 largest were never more than 8 /* in length by about 5 fi in 

 breadth at the widest part of the body. It was at first 

 thought that, owing to their pale colour, they were merely 

 capsules ot" some hiemogregarine that had left the host-cell ; 

 but, as no other forms were found anywhere else free in the 

 plasma, and as also the cytoplasm, even after prolonged 

 staining, was of the })alest blue*, they were their taken to be 

 definite parasites. Moreover, a small nucleus of the diffuse 

 type could with difficulty be made out. This was very small, 

 and not, as a rule, centrally placed, but occupied a i)lace iu 

 the cytojdasm at one end of the cell-body. Sometimes, as in 

 the other parasites, two forms were found in a single host- 

 cell. These either lay side by side or overlapped one 

 another when on one side of the nucleus ; but they often 

 occurred away from one another and on opposite sides of the 

 nucleus. Iso metachromatinic granules were present in this 

 organism. From the paleness of the coloration of these 

 parasites and from their badl}' staining diffuse nucleus, it 

 was at first thought that they were the microgamctocytes of 

 the forms found in the lymphocytes; but this seemed hardly 

 likely, since they were found by themselves in one fish. 

 Besides this, these forms were smaller and differed markedly 

 from the others in shape and in their disposition towards the 

 host-cell nucleus. It also seems inconceivable that two types 

 of the same parasite should choose different host-cells. 



It is a ditiieult matter to deterniiue the true character of 

 these parasites, but it seems that the organi.-ms in the erythro- 

 cytes are, at any rate, lla^mogregarines, the character of the 

 otlier specimens being decidedly uncertain. 



Parasites of Raia batis {the Common Skate). 



In the single fish examined a large number of small 

 Haniogregarines were found. They were so numerous in 

 the blood that at least 10 % of the erythrocytes were found 

 to be infected, and occasionally a few parasites w^ere found 

 free in the plasma. T hey were all small veiiiiicular forms, 

 measuring about 7 /x in length by about 2 fi in breadth. In 

 some cases the parasites were pointed at both ends (see 

 PI. XYH, fig. 2, 1 6i 2)^ but more usually one end was 



* The paleness of the cytoplasm was reminiscent of that exhibited by 

 certain Piroplasmata, but the nucleus was not nearly so prominent. 



