192 



SPOEOZOA. 



worms, and usually occur associated in great numbers.^ 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- 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 



Fig. 95. — GTega,Tmes. [A) Mono- ° i i , 



cystis agilis, from the testes of a nucleolus, and IS suiTounded by a 

 the eafthworm ; {B) Gregarina porous cuticle, under which may be some- 



cuneata, from the intestme of ' . • t i ,i • ^ 



Tenehrio; (C) stylorhynchus oli- timcs distinguished a tliiu, clear, some- 

 gacanthus, from the intestine of a ^^jj^gg striated, Outer layer. The formation 



dragou-fiy. 



or 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. — Enoapsuled Gregarines. {A) After conjugation ; 

 (B) After formation of pseudonavicellse. 



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



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

 Frantzius, " Oljservationes quasdam de Gregarinis,"' Wratislav, 1S46 ; Stein, "TJeber 

 die Natur der Gregarinen," MuUer's Arckivf. Anat. u. Physiol., p. 182, 1848 ; and Aim^ 

 Schneider, " Contribut. k I'hist. des Gregarines," ArrJiiv. d. Zool. expCr., t. iv., p. 493 et 

 seq., 187B. 



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