DISEASES OF POULTRY. 



193 



variola, allied to cow pox if not identical with it. 

 Careful study has shown, however, that it is an en- 

 tirely distinct disease. Some persons lacking a better 

 name have called it warts. More recently it was de- 

 scribed by Bollinger as epitheliotna contagiosum and 

 was by him and others supposed to be caused by the 

 low forms of animal parasites known as psorospertns. 

 The disease has, therefore, been called by some writers 

 cutaneous psorospermosis. In 1897, Sanfelice published 

 a notable paper on the subject from which it appears 



Fijf. 55. Fig-. 56. 



Fig. 55. — Inoculated pigreon 6 days after appearance of first symptoms. 

 Fi^. 56.— Inoculated pig-eon 10 days after appearance of first symptoms. 



that chicken pox is caused by a fungus of the group 

 now known to scientists as blastomycetes. 



Chicken pox affects ordinary fowls, turkeys, pig- 

 eons, and, more rarely, geese. Pigeons, and young 

 cjiickens are particularly susceptible. Grown fowls 

 are only occasionally affected. The malady while 

 widespread and well known is a disease of warm 

 countries, and is usually found in Southern Europe 

 and the Gulf Section of the United States. It is there 

 very destructive, attacking a large proportion of the 

 birds, and unless it is early and vigorously treated it 

 causes much damage and many deaths. 



Symptoms. — This disease chiefly affects the head 

 of poultry, and appears as an eruption of round or 

 oblong, yellow nodules, varying from the size of a pin - 



