— 17 — 



f The investigators referred to conducted experiments regarding the transmis- 

 sion of poliomyelitis from one monkey to another through the medium of Sto- 

 moxys. It was satisfactorily demonstrated that poliomyelitis could be transmitted 

 in that way. 



The causal organism has not yet been definitely isolated, although Doctors 

 Flexner and Xoguchi have recently obtained in cultures extremely minute bodies 

 of variable size and appearance which they believe may be the causative organism. 



The stable fly : Adult female as seen from above. 

 Greatly enlarged. (Howard) 



Tsetse-flics and Trypanosomiasis. — Tsetse-flies (Glossina spp.) are not 

 native of America, but belong to tropical and sub-tropical Africa. They are blood- 

 sucking flies, closely related to stable-flies, and in recent years have been shown 

 to be causally related to severe diseases of both man and domesticated animals. 

 Dr. Bruce made the important discovery that Nagana, a very fata'l disease to horses, 

 cattle, dogs and donkeys in South Africa, was produced by a trypanosome carried 

 to the blood by the bites of tsetse-flies. These trypanosomes are flagellate proto- 

 zoa, and when they occur in the blood of certain warm-blooded animals set up a 

 disease called trypanosomiasis. They are carried from one host to another by cer- 

 tain invertebrates, such as mosquitoes, lice, fleas and especially by such blood- 

 sucking flies as the tsetse-flies. 



The Nagana disease is caused by Trypanosoma brncei and the tsetse-flies 

 mostly concerned are Glossina morsitans and G. pallidipes. 



In the Congo Basin of Central Africa the terrible "sleeping-sickness" dis- 

 ease carries ofif tens of thousands of natives every year. Doctors Forde and 

 Dutton isolated the specific causal organism of this disease, which was named 

 Trypanosoma gambiensc, and Bruce and Navarro traced the organism to the bite 

 of the tsetse-fly, Glossina palpalis. Folsom states : "In the first stage of the dis- 



