EGG-SHAPED PSOBOSPEEMS. 



197 



pressure) as a mobile amoeboid organism (Fig. 99, B), as has been re- 

 peatedly observed both by Lieberkuhn and Balbiani. Since Lieber- 

 kiihn found these empty shells not unfrequently even within the 

 Psorosperm-saccules, and further saw the latter penetrated and sur- 

 rounded by amoeboid bodies, which agreed perfectly with the hyaline 

 balls previously liberated outside, it is probable that the young 

 parasitic brood sometimes escapes even within the host. 



A third group of Sporozoa consists of the so-called " egg-shaped 

 Psorosperms," which are of special interest to us, since they occur as 

 parasites, and, under certain circumstances, as dangerous parasites, in 

 Mammalia, and even in man. They are not, 

 however, by any means confined to the higher 

 animals, for many species are found in Inverte- 

 brata, e.g., in the common garden snail, in which 

 a form of this kind was discovered more than 

 twenty years ago by Dr. Kloss in Frankfort, 



and accurately followed through all its stages. x Gudus lota ; JB, from the gills 

 The term "Psorospermise," given to these para- with the ameboid 



sites, is of course only slightly suitable, for the ^s out (*&*** Lieberkuhn). 

 body thus denoted is not comparable to a germ or spore, but represents 

 the Gregarinoid mother-animal, inside which the true Psorosperms are 



FIG. 100. Coccidia from the intestine of the domestic mouse. A, inside an epith- 

 elial cell, still without a capsule ; B, C, encapsuled with Psorosperm and germ ; D, E, F, 

 isolated Psorosperms ; G, amoeboid brood (after Eimer). 



afterwards developed. The only thing which recalls the Psorosperms 

 is the firm shell, with which these surround themselves at the close 

 of their period of growth, a structure evidently analogous to the cap- 

 sule of the quiescent Gregarine, which establishes here also the exis- 

 tence of an encapsuled resting-stage. In this state the parasites so 

 closely resemble the eggs of certain intestinal worms, that they have 

 often been mistaken for them even by experienced microscopists ; 



1 "Ueber Parasiten in der Niere von Helix," Abhandl. d. Senkenberg. naturf. Ges- 

 , Bd. i., p. 189 ct seq., 1855. 



