172 



THE SPOROZOA 



that the Coccidia or Haemosporidia do. Though a given host often 

 contains a considerable number of Gregarines, it must be sup- 

 posed that they represent simply the batches of sporozoites derived 

 from several distinct infections. The epithelial cell that each 

 individual Gregarine has destroyed is not missed, and the injury 



FIG. 11. 



Effects produced on epithelial cells by the trophozoites of a 

 Gregarine (Pyxinia fremeli, Lav. et Mesn.) (par. Attagenus pellio, 

 larva). A, hypertrophy of the cell (first stage). B, atrophy (second 

 stage). Combined after figures by Laveran and Mesnil. 



FIG. 12. 



Portion of a section through the apparatus of fixation of a 

 Pterocephalus, showing root - like processes extending from the 

 Gregarine between the epithelial cells, which are not modified or 

 altered in any way, but appear to be under the influence of traction 

 exerted by the Gregarine. g, head of the Gregarine ; r, root-like 

 processes ; ep, epithelial cells. (After Siedlecki, x 500.) 



FIG. 13. 



Trophozpite of Larikes- 

 teria ascidiae (Lank.) 

 (par. dona intestinalis), 

 attached by an anterior 

 pseudopodium-like pro- 

 cess to an epithelial cell 

 (ep'), which is withered 

 and apparently destroyed 

 by it. ep, normal epithe- 

 lial cells. (After Sied- 

 lecki, x 500.) 



is easily repaired. The nutriment that the Gregarines absorb in 

 the gut of the host seems to be a tax lightly borne. There is, in 

 short, no record of any pathological effects produced by these 

 parasites beyond those already noted in the case of the host-cell. 



Morphology and Life-history. Since a typical Gregarine has 

 already been described in Monocystis, it is only necessary to review 



