206 COCCIDIUM OVIFORME. 



The one is more slender, and filled with uniformly diffused granular 

 contents ; the other is thicker and provided with a granular ball, which 

 has a diameter of 0*017 mm., and lies in the middle of the internal 

 space, leaving a great part of it free. The latter contains a clear 

 fluid, which is easily coloured by staining fluids, and acquires in time 

 a somewhat firm consistency. One can not unfrequently recognise in 

 the granular mass of the ball another clear sphere of varying size, 

 which one would at once consider as a nucleus if it were more sharply 

 defined and allowed itself to be stained. In point of fact, however, it 

 can hardly be otherwise described than as a drop-like aggregation of 

 the clear ground substance which connects the granules together. I 

 have never been able to find a genuine nucleus. 



The appearance of the contents exhibits many other differences in 

 detail. In the majority of Coccidia it is throughout of a finely granular 

 nature, but in other cases the protoplasm contains a more or less con- 

 siderable number of coarser granules, which are strongly refracting, 

 and not unfrequently flow together into larger masses like fat-granules. 

 Since Coccidia thus altered are much more common among forms which 

 have been cultivated than in fresh material, and since I have never 

 observed them to undergo any further change, I conclude that they are 

 dead specimens. The distinctively greater narrowing of one end is 

 hardly noticeable in the slender forms, and similarly the so-called micro- 

 pyle is for the most part, and that constantly, found in those of bulging 

 shape. Even the character of the shell varies, and is not unfrequently 

 double (Fig. 106, A), in the slender Coccidia. The outer wall is thinner 

 than the inner, which agrees exactly with the shell of the bulging forms, 

 both in its appearance and in its micropylar arrangement. Since there 

 are also specimens in which the outer shell is represented only by a 

 delicate more or less distant border, and others which are provided 

 only with a simple completely closed shell, this lends some support 

 to the opinion that the Coccidia in certain developmental stages cast 

 their skin, and afterwards assume the bulging form, with micropyle 

 and central mass of granules (Fig. 106, B). If we regard this shell 

 (which is provided with a micropyle, and perfectly resembles an egg- 

 shell in its refractive power and double contour) as a kind of capsule, 

 then the previous thinner coating may perhaps represent the true 

 cuticle. However, the fact that the capsule wall would then arise 

 under the cuticle, and not from it, as in the Gregarines, seems hardly 

 in favour of this opinion. 



The formation of the body here described does not take place 

 freely in the interior of the enlarged bile-duct, but in its epithelial 

 lining. Although Stieda declared that he had never seen such a 

 mode of origin, and Waldenburg affirmed the same in regard to the 



