184 PROTOZOAN PARASITISM 



They are about 8 to 15 microns long, are of an 

 elongated ovoid shape with rather bluntly rounded 

 ends, and are of a "ground-glass" appearance. In 

 one end are the nuclei which may be seen on careful 

 observation, reminding one of eyes. In iodine solu- 

 tion, showing the cyst wall, the brown body, with 

 the nuclei and the flagellar apparatus more or less 

 distinct, the cyst can hardly be confused with any- 

 thing else. Uniformly sized ovoid "ground-glass" 

 bodies with "eyes" in one end are likely to be Giardia 

 cysts. 



In preparations stained with the iron-haematoxy- 

 lon method, specimens showing rather clearly the 

 intricate flagellar system, the nuclei, the cytostome, 

 the axostyles, are obtained without great diffi- 

 culty. 



The oral sucker is composed of two discs or shield?, 

 outlined by stiff marginal fibers. There are two nu- 

 clei in the cytoplasm, one about the middle of each 

 shield, each with central karyosome. The anterior 

 pair of flagella arise from the blepharoplasts and af- 

 ter passing forward for a way, decussate and round 

 the margins of the oral sucker, becoming free after 

 traversing about one third of the margin. The two 

 middle pairs of flagella come from about the junction 

 of the two lateral shields posteriorly, one pair pass- 

 ing directly backward, the other diverging. The two 

 posterior flagella are the free fibrils, coming from 

 that extremity of two stiff fibers, the axostyles, pass- 

 ing straight up the middle of the body to the blepharo- 



