SECONDARY WANDERINGS. 



69 



merely to assist their wanderings are cast off, and replaced by new 

 structures, which subserve their altered conditions of life. Asa general 

 rule, Entozoa, in this second developmental stage, show a considerable 

 likeness to the fully formed ani- 

 mals, but differ in various direc- 

 tions. The sexual organs, for 

 instance, are incompletely de- 

 veloped, or even absent, so that 

 the organization is, on the whole, 

 less differentiated, — in accor- 

 dance, certainly, with the com- 

 paratively simple and uniform 

 conditions of life. The embryos 

 remain quiescent, and imbedded 

 in the tissue of organs, generally 

 within a cyst, which, as we have 

 seen, is formed by growth of 



Fio. 46. — A piece of liver from the rabbit, 

 showing passages made by Oysticercns pisi- 

 formis. 



the connective tissue, or secretion 



FlO. 48. — Aspidogaster coiKhicola. a. Embryo ; 

 b. Young animal, not sexually mature (after Aubert). 



Fig. 47. — Archigctei Sieioldi. 



by the growing body of the parasite, and feed on the substances 

 immediately surrounding)/^gj(^^|5./l^^so/?® 



