POUIvTRY DISEASES AND THEIR TREATMENT. 185 



With this disease revealed the presence of large numbers of 

 protozoan organisms which he identified as Coccidiwn tenellum. 

 At practically the same time Drs. Cole and Hadley of the Rhode 

 Island Experiment Station reported finding a similar organism 

 in white diarrhea chicks. They identified it as Coccidium cuni- 

 ciili. These two species of coccidium are so nearly alike that it 

 is very difficult to distinguish them except by prolonged study of 

 their life cycles. Various species of coccidia have long been 

 known to infest many domestic animals. In all cases that have 

 been studied they produce very serious diseases. 



The life history of a coccidium is very complicated yet in or- 

 der to combat this parasite most successfully it is necessary to 

 know something of its life history. Fig. 44 represents the dif- 

 ferent stages in the life history of these parasites. If one should 

 examine with a microscope the contents of one of the ceca of a 

 chick which died with this form of white diarrhea he would find 

 forms somewhat like No. i in the figure. These are the oocysts 

 or permanent cysts of the coccidium. The membrane around 

 the outside of this cyst is very tough and will withstand almost 

 all methods of disinfection. It will live and even grow in sul- 

 phuric acid. It can be killed, however, by drying. The size of 

 these cysts is about 14-25000 inch and 21-25000 inch. If this 

 cyst is placed under the right conditions for development the 

 first step is for the protoplasm to divide into 4 spherical bodies 

 which are called sporoblasts (fig. 44, 2). Each of these sporo- 

 biasts then divide into two sickle-shaped sporozoids (cf. fig. 44, 

 3 and 4). These sporozoids are then set free in the intestinal 

 tract (4a) and each one penetrates with its pointed end an epi- 

 thelial cell of the intestine as at No. 5. In the figure 5a, 5b, 5c, 

 6 and 6a, represent the succeeding stages of growth of the or- 

 ganism within the intestinal cell. As shown in 6a and 7 the 

 parasite grows so large that it completely fills the cell and finally 

 these cells are broken down and torn off the intestinal wall. 

 The stage of the parasite shown at 6a and 7 is known as the 

 schizont. The next step is for the schizont to break up into 

 a larger number of sharp pointed bodies as shown at 7a. These 

 escape and enter other epithelial cells just as the somewhat sim- 

 ilar bodies did at 5. At .this point the organism may do one 

 of two things. The small sporozoids from 7a may develop 

 exactly like the sporozoids did from 5 to 7. This part of the life 



