96 Diseases of Poultry 



Experiment Station have claimed that the causative or- 

 ganism belongs to another group of protozoa known as 

 Coccidia. The point to the discussion as to the cause of this 

 disease lies in the fact that the Coccidium has a very different 

 life history (cf. p. 73) from the Amoeba, consequently it 

 has different methods of dispersal and different means must 

 be used in combating it. 



Cole and Hadley claim that the amoeba described by 

 Smith is one of the stages in the life history of the coccidium. 

 Smith, however, in a more recent paper ^ reaffirms his posi- 

 tion with regard to the amoebic cause of the disease. He 

 claims that the Rhode Island authors have confused the 

 fact that coccidia are frequently present in birds as an 

 entirely separate infection. He states that there is " ample 

 evidence to show that enterohepatitis may run its course in a 

 flock without the presence of a single coccidium cyst to sug- 

 gest coccidiosis. It is evident that coccidiosis among birds 

 has been frequently seen during the past 30 years but with- 

 out involvement of the liver." 



These criticisms by Smith were partially answered by 

 Cole and Hadley ^ but the chain of evidence presented by 

 them is far from complete. Not until the complete life 

 history of the coccidium has been worked out will there be 

 conclusive evidence as to whether or not it is concerned in 

 this disease. In the meantime it appears that the conten- 

 tion of Smith is well founded, viz., that the amoeba and the 

 coccidium are separate entities and that the latter when 

 present is only a secondary infection. 



The method of infection by the amoeba is as follows, the 

 account being based upon that given by Salmon {lac. cit.) : 



1 Smith, Theobald, "Amoeba meleagridis." Science, N. S., 

 Vol. 32, pp. 509-512, 1910. 



- Cole, L. J., and Hadley, P. B., "Amoeba meleagridis." Science, 

 N. S., Vol. 32, pp. 918-919, 1910. 



