SPOROZOA 



429 



Fig. 188. — El- 

 mer i a steidae. 

 06cyst containing 

 four spores, 



forms about the fertilized cell and within this the cell divides 

 into two and later into four embryo parasites, which are enclosed 

 in pairs in two spores within the cyst. This escapes with the 

 feces of the mole and serves to infect a new host. 



The invasion of the epithelium produces a severe diarrhea in 

 the mole often resulting in death. If the animal survives for 

 five days, until after the spores are formed, it 

 then usually recovers. 



Eimeria Stiedae (Coccidiiun Cuniculi). — This 

 very common parasite of the rabbit was first de- 

 scribed by Lindemann in 1 86 5 . It lives and grows 

 within the epithelial cells of the small intestine, of 

 the bile passages and of the liyer of rabbits suffer- 

 ing from coccidiosis, and its oocysts are found in 

 the intestinal contents and in the feces of such 

 animals. The oocyst is an elongated oval, vari- 

 able in width from 11 to 28^1 and in length from 

 24 to 49M. It contains, when fully developed, four each of which two 



,,.,., , . , ■, sporozoits are de- 



spores, each 01 which contams two embryo para- , veloping. The 

 sites or sporozoits. These gain entrance to the ™=ropyie is be- 



^ ° low. (From Do- 



mtestine of a new host along'with the food and the flein after Metz- 

 pancreatic digestion makes an opening at one end 

 where the wall is exceedingly thin, the micropyle, and through this 

 opening the wedge-shaped sporozoits escape. They penetrate epi- 

 thelial cells, in which the parasite becomes rounded and grows to a 

 diameter of 20 to 50/x, destroying the host cell. The nucleus 

 divides many times and after it the cytoplasm, so as to form numer- 

 ous spindle-shaped young cells, merozoits or agametes, which 

 penetrate new epithelial cells and pass through the same cycle. 

 This cycle of asexual multiplication, schizogony, is repeated many 

 <times and may lead to extensive destruction of intestinal mucosa, 

 of the epitheUum of the bile ducts and of liver substance. Some of 

 the growing parasites become differentiated into sexual elements. 

 The female cell, macrogametocyte, accumulates numerous large 

 granules in its cytoplasm, and when full-grown the chromatin 



