AufiUSt, '12] BRUES AND .-^HEPPARD: INFANTILE PARALYSIS 313 



time spent outdoors by the children for the same reason, and because 

 many are in school during a great part of the day soon after the first 

 of September. It seems to us, therefore, that the fact cannot be 

 ignored that the greatest seasonal expression of acute epidemic poli- 

 omyelitis agrees strikingly with the greatest growth of Stomoxys and 

 the school vacation peiiod when children of all ages live a compara- 

 tively out-of-door life in parks, in bathing, etc. There is one habit 

 of Stomoxys which should receive consideration also. In feeding, it 

 very regularly passes from animal to animal during a single feeding 

 and the opportunities for it to transmit micro-organisms in a mechani- 

 cal way upon its mouth-parts are thus greatly increased. 



It thus appears impossible upon a priori grounds to rule out Sto7noxys 

 and a final decision must await the results of experiments now in 

 progress in which an attempt is being made to transmit the disease 

 among monkeys by means of Stomoxys. 



It is interesting to note in connection wHh the above remarks on 

 Stomoxys, that it may quite possibly be associated with the spread 

 of equine infectious anemia. The initial attack of this disease usually 

 occurs in July, August and September and no causal relation appears 

 to exist between its incidence and such ordinary sources of infection as 

 food, water or contact. It is a blood disease, not infectious through 

 ingestion of the virus into the alimentary tract, but readily communi- 

 cable by intravenous inoculation. Such conditions immediately sug- 

 gest Stomoxys, or possibly, but less probably, Hcematohia, or Tahanus, 

 as carriers, especially since experiments with Margaropus annidatus, 

 the carrier of Texas Fever, have given negative results. 



Belonging to another closely related family, the Anthomyidse, is a 

 much smaller insect known as the horn-fly {Hmmatohia serrata) w^hich 

 exhibits biting propensities similar to those of the stable fly, but con- 

 fines its blood-sucking almost exclusively to domestic animals. On 

 this account it is almost entirely restricted to barnyards and pastures 

 or more rarely to stables where the adults attack the animals and gorge 

 themselves with blood. In visiting cases of anterior poliomyelitis 

 during the summer of 1911 we have looked for this fly, but found it in 

 the neighborhood in only a very few^ instances. This fact, coupled 

 with its rare occurrence upon man, renders its association with polio- 

 myelitis very unlikely. 



There remain several other groups of biting Dipt era; one of them, 

 the horse flies (Tabanidse) have been associated with several diseases 

 of domestic animals. None are known to be specific carriers, but on 

 account of their blood-sucking habits may carry the virus of diseases 

 in a casual way from one animal to another. It is possible that these 

 Tabanidse may also take part in the transmission of anterior poliomye- 



