Miscellaneous, 195 



I have met with two species — one in the liver of the stickleback, 

 the other in the testis of the sardine. Both belong to the genus 

 Coccidmm, as characterized by the successive works of Leuckart, 

 Schneider, and lialbiani ; that is to say that, on arriving at their 

 full development, they form four spores, each of which encloses 

 two falciform bodies. 



(i.) Ooccidid of the SticMebach (Coccidium gasterostei, sjj. n.). — I 

 discovered this species in April of the present year in sticklebacks 

 (Gasterosteus acideatus) from the marshes of Yilaine, in the Morbi- 

 han. This Coceidid is of small size and its cysts only measure 16 

 to 18 /Lt, It lives in the hepatic cells, undergoing the whole of its 

 development in the same cell. I have several times observed cells 

 containing three or four cysts. These facts are easily made out by 

 teasing a portion of diseased liver. By making sections of the 

 organ, after fixing, hardening, and embedding it in parafiin, I have 

 been enabled to discover the developmental phases and to study 

 them much more easily than by teasing ; but it was by means of 

 the latter method alone that I succeeded in determining the exact 

 relations of the parasite to the hepatic cell. I have not been able 

 to observe the very young stages. On attaining its full develop- 

 ment Coccidium gasterostei measures, as I have already said, 16 to 

 18 /J. in diameter. It is a little spherical mass of plasma enclosing 

 a very large number of coarse globules ; these are tolerably refrac- 

 tilc, but do not affect polarized light. 



At this point the Coccidium encysts, that is to say the plasma 

 surrounds itself with a delicate transparent pellicle of a uniform 

 spherical shape. The plasmic mass then contracts, leaving an 

 empty space between it and the wall of the cyst. The nucleus lies 

 in the centre of the plasma, though the granulations of the latter 

 sometimes render it difficult to determine its presence. After a 

 short time it migrates to the periphery and diWdes. The small 

 size of the nucleus renders the task of observing it an extremely 

 delicate one, and I have therefore not been able to follow all the 

 stages of its division ; I have, however, found figures sufficiently 

 distinct to enable me to recognize karyokinesis. 



The two nuclei resulting from this division divide in their turn, 

 and we finally get four nuclei placed at the extremities of two 

 perpendicular diameters of the plasmic sphere. The latter then 

 splits up into four little spheres, each of which encloses a nucleus. 

 This segmentation of the primitive mass appears to take place very 

 rapidly, and most probably in the majority of cases it does so all at 

 once. There is sometimes a second stage, which, bj^ reason of its 

 extreme rarity in my preparations, is probably a very short one, 

 that is supposing it to be constant. The four little nucleated 

 spheres are sporoblasts. Their nucleus divides (always indirectly) 

 and the binuclear sporoblasts then lengthen out, surround themselves 

 with an envelope, and reassume the characters of typical spores of 

 Coccidium, that is to say, each of them encloses two falciform bodies 

 provided with a nucleus. During the formation of these sporozoids 

 there is to be seen a residual granular mass, which diminishes little 

 by little during their increase in size (Schneidei''s residue). The 

 mature spore is fusiform in shape and 10 fx long by 4 to 6 /,< wide. 



