C. M. Wenyon 
289 
puppies to full grown dogs. It was impossible for the young puppies 
to have suffered from the disease, so that the ordinary dogs of the 
Bagdad streets must have a natural I'esistance to the disease as inocu¬ 
lated experimentally. The inoculations were carried out in various 
ways. Some of the dogs wei’e inoculated by scarification and appli¬ 
cation of fluid from a sore; others were inoculated into the skin with 
the hypodermic syringe. They were inoculated both on the skin of 
the nose, on the inner surface of the thigh, or on a shaved patch on the 
back. In none was a soi’e produced. In two dogs, in one case on 
the nose and in the other on the leg, a superficial ulceration was 
produced at the point of inoculation cpiite unlike a sore and in which 
the parasite could not be discovered, even after repeated examination. 
This failure to infect dogs with the disease is strange after the 
successful inoculation of dogs by C. Nicolle and L. Manceaux in North 
Africa. These observers have found that dogs become infected about the 
nose after an incubation period of thirty-six days. The disease however 
is not of long duration, so that it is possible that my failure to inoculate 
means that the Bagdad dogs are naturally immune in a place where 
the disease is so common in man. Inoculation of dogs from artificial 
culture of the sore parasite was equally unsuccessful. 
Cats. Cats, like the dogs in Bagdad, though less numerous live in 
a semi-domestic condition. Only one of these animals was examined, 
and that with a negative result. 
Rats. Rats were exceedingly common and a great pest. The only 
protozoal parasite found in the blood or organs was the common 
Trypanosoma lewisi and the leucocytic haemogregarine. Inoculation 
of numbers of rats with material from the sores and blood agar cultures 
has given no result. 
Rabbits. Similar experiments conducted on rabbits have given no 
result. 
Birds. Sparrows and two small owls were likewise inoculated 
without success. 
Ticks. An attempt was made to obtain a development of the sore 
parasite by inoculating the large blown-out ticks taken off dogs. The 
ticks survived the operation of inoculation, which was made with a fine 
needle into the abdomen, but no trace of any developmental forms of 
the parasite could be found when the contents of the ticks were 
examined microscopically. 
Other domestic animals in Bagdad are the horse, mule, donkey, and 
cattle. Camels are rarely seen in the town, and then only in passing 
19—2 
