16k 



of tularemia "by the blood-sucking deer fly, Chrysops 

 discalis . This was followed lay similar reports "by Francis 

 and Lake (1921, 1922a, 1922b) involving the rabbit louse, 

 Haemodipsus ventricosus , the bedbug, Cimex lectularius, 

 and the mouse louse, Polyplax serratus . 



During the years 1922 and 1923, Parker, Spencer, and 

 Francis (192*0 made observations which indicated the 

 spontaneous occurrence of the tularemia organism in the 

 tick Dermacentor andersoni . They also demonstrated stage- 

 to-stage transmission of the "bacterium from larva to adult 

 tick. Later, Parker and Spencer (1926) proved the heredi- 

 tary transmission of Pasteurella tularensis ( Bacterium 

 tularense) in Dermacentor andersoni . This appears to have 

 been the first recorded instance of the hereditary trans- 

 mission of a known pathogenic "bacterium "by an arthropod. 



Parker and his associates (Davis, Philip, and Jellison) 

 have made numerous other studies regarding the association 

 of arthropods and the tularemia "bacterium. As to their 

 findings, we quote . from Parker (1933)-' 



"(a) The demonstration of the survival of Bact . 

 tularense from the larvae through to the adults of 

 "both H. leporis-palustris and D. variabilis , its 

 transmission "by the successive stages involved, 

 and generation-to-generation transmission from in- 

 fected females to their progeny. 



(Id) Larval to adult survival in, and transmis- 

 sion "by, the successive stages of the brown dog 

 tick, R. sanguineus , and the lone-star tick, A. 

 americanum , within a single generation. 



(c) Survival in, and later transmission "by 

 adult rabbit dermacentor, D. parumapertus marginatus , 

 and the Pacific Coast tick, D. occidentalis , that 

 had previously ingested virus. 



(d) Mechanical transmission to guinea pigs "by 

 Ta"banus septentrionalis , "by another species of 

 horsefly tentatively identified as T. rupestris , 

 and by Chrysops noctifer , and the survival of viable 

 Bact . tularense in C. noctifer for a period of over 

 a month. Survival only was also shown in an unde- 

 termined species of Ceratopogonidae. [Philip, un- 

 published experiments.] 



(e) Failure to transmit infection by species 

 of fleas occurring in the native Montana fauna. 



(f ) Mechanical transmission by immediate inter- 

 rupted feeding by the black fly, Simulium decorum 

 katmai. [Philip, unpublished experiments.] 



(g) Transmission by the sucking louse, Neohae - 

 matopinus laevius cuius , of the Columbian ground 

 squirrel. 



