134 THE ANIMAL PARASITES OF MAN 



membrane, the sporocyst. Nuclear division occurs inside the sporo- 

 cyst by a series of three binary fissions (fig. 64, e), so that each sporo- 

 cyst, now usually referred to as a spore, contains eight nuclei. The 

 cytoplasm collects around each nucleus and eight vermicular sporo- 

 zoites are produced within each spore (fig. 64, /), thus completing 

 the life-cycle. 



It will be noticed that in the above life-cycle no asexual multipli- 

 cation occurs. These organisms, such as Monocystis, are known as 

 the Eugregarines, and include the majority of the gregarines. The 

 remainder, which have introduced schizogony into their life-cyle, are 

 known as the Schizogregarines. 



There are variations in the morphology and life-cycle of gregarines 

 besides those that have been mentioned. It is not within the scope 



FIG. 66. Spores of various Gregarines. a, Xipho- 

 rhynchus. b, Ancyrophora. c, Gonospora. d, Cerato- 

 spora. (After Leger.) 



of this book to discuss them in detail, but the following may be 

 noted : 



Morphological differentiation of gametes may occur as in Stylo- 

 rhynchus oblongatus (fig. 65), which differentiation is probably of a 

 sexual nature. 



The sporocyst really consists of two layers, an epispore and an 

 endospore. Externally the spores of different gregarines show great 

 variety in shape and markings, and spines, or long processes may 

 be present (fig. 66). 



The resistant spores serve for the transmission of the gregarines 

 from host to host. The mode of infection is contaminative, the 

 spores expelled with the dejecta of one host being absorbed with the 

 food of a new host. 



The Gregarinida may be classified as follows : 



Sub-order I. Eugregarinea, without schizogony. 



Tribe i. Acephaliua. Without an epimerite and non-septate ; 

 often " ccelomic " (body-cavity) parasites. E.g. : Monocystis, with 



