u8 SOME MINUTE ANIMAL PARASITES 



parasite and by the intimate relation that exists 

 between it and its host. 



If a small piece of excrement, about enough to 

 remain on the tip of a pin, is taken from a grouse or 

 fowl victim of coccidiosis, rubbed in a drop of water, 

 and the liquid examined microscopically, a number 

 of small, oval, shining bodies are seen mingled with 

 the vegetable debris. Dust from plants in the neigh- 

 bourhood (e.g., heather sprays) will often show 

 these same bodies under the microscope. Every 

 one of these oval structures or cysts is capable of 

 forming four more, termed spores, within itself, and 

 concealed in each of the four spores are two malig- 

 nant germs, ready to issue from the spore under the 

 influence of the digestive juices of a bird that has 

 swallowed the spore. Once set free, they commence 

 their work of destruction of the intestine, and by 

 their enormous powers of multiplying within the 

 lining of the gut soon reduce it to a structureless 

 pulp (Fig. 27). Digestion is thus deranged, the 

 whole system becomes affected, emaciation and 

 anaemia proceed apace, and ultimately the victim 

 dies. 



Such is the usual course of affairs. Externally 

 there is little at first to distinguish a healthy from 

 an infected chick, but as the disease proceeds, great 

 loss of weight occurs. This is very marked in some 

 cases. For instance, of two sister chicks of the 

 same age and originally of the same weight, one 

 became infected and the other remained healthy. 

 At the time of death of the infected bird its weight 

 was 5 ounces, while its healthy sister chick weighed 



