90 



PEACTICAL PABASITOLOGY 



Where this is impossible, the portion of intestine should be kept in 



a thermostat at a temperature of 37 to 38 C. 



It is very rare to find the intestine of swine 

 free from Balantidia. The living organism is 

 best seen by diluting a small quantity of the 

 bowel-contents with normal saline solution, 

 which has been previously heated to 37 C. 

 The Infusoria may be seen with a low-power 

 lens and are readily distinguished by their 

 movements. The structural details are only 

 to be seen with a strong glass. The parasite 

 differs somewhat from B. entozoon ; the peris - 

 tome is shorter, the individual cilia are shorter, 

 and there are only two contractile vacuoles 

 (fig. 27). If the material is allowed to cool, or 

 if the portion of intestine is kept for a time 

 before examination, round cysts of Balantidia 

 will be found, while the free forms will be pro- 

 portionately fewer. Occasionally it is possible 

 to follow the actual process of encystment 



FIG. 27. Balantidium 

 coli, from an ulcer of the 

 large intestine of man. 

 Magnified,600:l. (Original.) 



under the microscope. 



(c) Infusoria found in the Stomach of Ruminants and in the 

 Ccecum of the Horse. 



A large and interesting variety of Infusorians is found in the rumen 

 and reticulum of ruminants. The stomach of a freshly killed animal 

 should be punctured, and the fluid which flows from the perforation 

 (it should be fairly free from food-remnants) is caught in a glass-tube. 

 This should be wrapped in a cloth and carried in the pocket to the 

 laboratory. If kept in a thermostat at a temperature of 35 to 36 C. 

 the Infusoria will live, certainly for one day, but never longer than 

 three, owing to fermentation of the stomach-contents. The objects 

 must be examined upon a warm table, as the greater number of the 

 Infusoria found in the stomach of ruminants possess a retractive 

 peristome, which is only released under the influence of a certain 

 degree of warmth. A temperature of about 30 C. is sufficient, and 

 this will also slightly reduce the extreme motility of the organisms. 

 For preservation, a small quantity of the material is put into a warm 

 glass and hot alcoholic solution of mercuric chloride is poured over it. 



The Infusoria which live in the gastric secretion belong to a large 

 number of different species, and are sometimes distinguished by their 

 bizarre form. They frequently put out stiff, thorn-like prolongations, 



