PROTOZOA 



137 



to the intestinal epithelium of the animal in which it lives. It is a cause 

 of diarrhoea in man, and also of a fatal disease of the intestines in 

 rabbits; but it is almost invariably found in the duodenum and first 

 portion of the small intestine of normal laboratory animals such as 

 mice, rats, and rabbits. 



FIG. 98. Lamblia intestinalis. A, Ventral view; N. t one of the two nuclei; ax.> 

 axostyles;^. 1 ,^. 2 , fl- 3 ,fl- 4 , the four pairs of flagella; s., sucker-like depressed area on 

 the ventral surface; x., bodies of unknown function. (After Wenyon (277) from 

 Minchin.) 



The SPOROZOA are parasitic protozoa which multiply by the produc- 

 tion of spores at some stage of their life cycle. There are very many 

 sporozoa and so, for convenience of classification, they are subdivided 

 into seven orders. The Gregarina have ajvery distinctive shape; the 

 single cell, of which they are composed, is divided into two or more 

 divisions. The first of these divisions is furnished with hooks or other 

 structures through which the parasite attaches itself to its host. None of 

 the gregarines are parasitic on mammals; worms are the hosts for some 

 of them. The Coccidia are usually parasitic within certain cells of their 



