152 INSECTS AND MAN 



it is probable that both diseases are bizarre forms of 

 piroplasmosis. Both diseases consist in the breaking up 

 of the red-blood corpuscles during the fever stage, with 

 resultant anaemia; both are confined to certain restricted 

 valleys in mountainous regions ; both cause swelling and 

 congestion of the liver and spleen ; both may be contracted 

 in places uninhabited by man; the primary reservoir of 

 infection, in both cases, is to be found in the native fauna ; 

 and both show every indication of being transmitted by 

 ticks. 



When disease-producing organisms pass into the gut 

 of a tick along with the blood of the host, some travel 

 to the salivary glands and some to the ovaries. Those 

 organisms in the salivary glands escape during the next 

 feeding of the tick and so transmit the disease ; those in 

 the ovaries are transmitted through the eggs to the next 

 generation of ticks, where they pass to the salivary glands, 

 in readiness to infect a new host, when feeding takes place. 

 The guilt has not yet been laid upon any one species of tick ; 

 in fact, a fly is now also suspected of being the carrier; 

 but Margaropus annulatus australis, from the bodies 

 of cattle, and Ornithodorus megnini, from the ears of 

 horses, cattle, and sheep, both of which occur in the 

 verruga locality, may be dismissed, because they pass all 

 their stages, including engorgement, on the same host. 

 It is to ticks of the genera Dermacentor, Amblyomma, 

 Rhipicephalus, and Hcemaphysalis, which live on small 

 hosts during the larval stage, and drop to the ground 

 during the nymph stage, to seek new hosts when they 

 become adult, that we must assign the probability of the 

 transmission of this fatal disease if it be tick-transmitted. 

 And the natural reservoirs of the disease organisms will 

 probably, eventually, be shown to be the Octodontidce and 

 Cricetince, relatives of the pocket and grasshopper mice. 



As recently as October 1913, a scientist, working in the 

 verruga district with a view to discovering its means of 



