ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 761 



tions of Aime Sclineider, E. van Beneden, &c. The views of Gabriel 

 are not noticed. In particular, the so-called Psorospermi^, and 

 among these the " oval Psorospermise," which occur not uncommonly 

 in mammals and sometimes even in man, are noticed with especial 

 care. Again, all that has been known since the time of Joh. Miiller 

 with regard to the " psorospermia-sacs " of fish and frogs is given at 

 considerable length, and their differences from, together with the 

 points connecting them with the true Gregarinae, are brought into 

 prominence. 



The egg-shaped Psorospermi^, observed in 1855 by Kloss in 

 Invertebrata (garden snail), and studied more minutely in the cuttle- 

 fish, Leuckart denominates Coccidia, and mentions the well-known 

 parasite of the liver of man and the rabbit under the name Coccidium 

 oviforme. It is not quite clear whether the author includes under 

 this generic title Coccidium those parasites also of the Invertebrata 

 and of some mammals, which have been mentioned in this connection, 

 and have been designated by A. Schneider as Klossia, Benedenia, and 

 Eitneria, for these names are also occasionally introduced. The 

 forms belonging to the genus Coccidium are characterized as devoid 

 of covering, and as inhabiting epithelial cells in their young condition, 

 but as becoming covered with a shell after growth is ended. In this 

 condition they emerge from the epithelial cells and in part abandon 

 their host. Within the shell the body deveiopes into from one to a 

 large number of spores, which in their turn develope bacillar or spiral 

 embryonic forms within themselves ; a part, however, of the original 

 granular contents of the spore generally persists in the form of the 

 so-called granular mass. 



We pass over the carefully elaborated views of former observers 

 as to the nature of the organisms in question, with their manifold 

 divergences of opinion, and from the detailed description of the organi- 

 zation and development of Coccidium oviforme we select the following 

 points. The two forms of Coccidia which are found free in the 

 so-called psorospermia-balls of the rabbit, namely, the more slender 

 form with its contents entirely filling the test, and the more capacious 

 form with contents contracted into a globular mass, are brought into 

 harmony with one another as different stages of development, that is, 

 the former represents the earlier condition, which produces a fresh 

 and capacious shell underneath the original one, which is ultimately 

 lost, and which deveiopes into the second form by contraction of the 

 contents into a ball. The bulky form is distinguished further by the 

 existence of an opening resembling a micropyle at the pointed pole of 

 the test and by the presence of a pale sphere in the globularly con- 

 tracted contents, which, however, Leuckart is unable to recognize as 

 a nucleus. 



With regard to the constitution of the psorospermia-balls taken as 

 wholes, they are the result of the widening of the bile-ducts and the 

 union of the walls across their lumina, the connective tissue in their 

 vicinity undergoing considerable proliferation. Various stages of de- 

 velopment point to the origin in this manner of the " balls " or 

 " knots " by fusion of neighbouring bile-ducts. The development of 



