192 



SPOROZOA. 



worms, and usually occur associated in great numbers. 1 In certain 

 animals, and especially in omnivorous species (Tenebrio, cockroach, 

 earthworm, &c.), they are almost constant, so that one can 

 hardly examine a specimen without finding Gregarines. They are 



harboured sometimes in the intestine, 

 as in insects, sometimes in other organs, 

 as in the testes of the earthworm, some- 

 times in the body-cavity. 



The body of the Gregarine 2 is more 

 or less extended, and often saccular. 

 The intestinal parasites are very con- 

 stantly provided with a pad or pro- 

 boscis like, sometimes even hooked, 

 process, which serves as an organ of 

 attachment, and if in the form of a 

 sucker, may connect two animals to 

 gether (Fig. 95, B). The protoplasm 

 is more or less granular, according to 

 the age and size of the parasite. It 

 encloses a large vesicular nucleus with 

 a nucleolus, and is surrounded by a 



FIG. 95. Gregarines. (A) Mono- 



cyatis agilis, from the testes of 



the earthworm ; () Gregarina porous Cuticle, under which may be SOIlie- 



cuneata, from the intestine of *. . * 



Tenebrio; (C) Styiorhynchus oK- times distinguished a thin, clear, some- 

 gacantkus, from the intestine of a times striated, outer layer. The formation 



of spores takes place at the close of the 



individual development, when the animal has attained its full size, 

 and has lost its attaching apparatus. It draws itself together into 

 a ball, and encysts singly or in pairs. In the latter case, after 



FIG. 96. Encapsuled Gregarines. (A) After conjugation ; 

 (B) After formation of pseudonavicellae. 



1 Hence the name Gregarina, from "Grex," a herd. 



2 For an account of the Gregarines, properly so called, see especially the researches of 

 Frantzius, " Observations qusedam de Gregarinis," Wratislav, 1846; Stein, " Ueber 

 die Natur der Gregarinen," Mutter's Archiv f. Anat. u. PhysioL, p. 182, 1848 ; and Aime* 

 Schneider, " Contribut. a 1'hist. des Gregarines," Archiv. d. Zool. cxptr., t. iv., p. 493 et 

 seg.,1875. 



