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months. Both the young larvae and nymphs are shiggish and not 

 capable of attaching themselves for some days. The nymph requires 

 3 to 6 days for engorgement and, lea\ang its host, becomes adult 18 

 days later and then gorges itself in 7 days. The adults have been kept 

 ahve in the laboratory for 14 months. R. simus also requires 3 hosts. 

 The eggs hatch in summer 30 days after oviposition. The larva 

 becomes a nymph in 20 days, and the nymph an adult in 25 days more. 

 Amhhjomma hebraeian, is also a 3 host species. In summer the female 

 lays her eggs 2 weeks after quitting the host, or 3 months in winter, 

 hatching taking place in about 10 weeks or 6 months respectively. 

 The larvae have been known to hve 7 months, and remain 7 days on 

 their host when found. Twenty-five days later the first moult occurs, 

 but if conditions are unfavourable this may be delayed for 4 months. 

 The nymph gorges itself in from 4 to 20 days and may live 6 months 

 without a host. The adult appears 25 days later in summer or as 

 much as 160 days in winter, gorges itself in from 10 to 20 days, and 

 may hve several months. 



The author then goes on to discuss the transmission of disease, which 

 is intimately associated with the mode of life of the tick. Where the 

 tick has only one host, the disease can only be transmitted to one host 

 by the same individual, but if the tick have two or three hosts it is 

 possible for the same tick to transmit the disease to different animals. 

 It is only by accident, or as the result of experiment, that a tick will 

 change its host in one of its stages. It appears however that male 

 ticks can and do pass from one host to another. 



The propagation of tick-borne diseases is greatly increased by the 

 capacity of ticks for transmitting infection to their offspring. This is 

 the case with piroplasmosis, anaplasmosis, and spirillosis transmitted 

 in South Africa by M. annulatus, as well as Babesia canis, transmitted 

 by Haemaphysalis leaclii. The infection acquired from the parent 

 does not reappear in some species except in the adult ; thus H. leach i, 

 though capable of hereditary infection, is not infective except in the 

 adult stage. Some authors believe that in the case of this tick it is 

 the only possible mode of infection, but Christophers is of opinion 

 that the adult tick, if fed in its nymphal stage upon a dog suffering 

 from piroplasmosis, can transmit the disease as an adult without 

 regard to any hereditary infection. 



Tick-borne diseases may be divided into two categories, those 

 which, after recovery, leave the animals still infected and a source of 

 contagion for the ticks, and those in which the cure is complete and 

 the parasites are entirely eliminated from the blood. In the first 

 category are the diseases due to : — Piroplasma bovis, equi, ovis, canis, 

 Anaplasma marginalis and centralis, Theileria. mufans, and spiril- 

 losis of cattle ; in the second category, East Coast fever {Theileria 

 parva) and heartwater. 



This explains the fact that animals impoited into a district in Africa 

 where there is no known case of acute piroplasmosis have acquired 

 the disease, the reason being that they are bitten by ticks w^hich have 

 been infected from animals which have recovered from the disease, 

 but are stiU carrying the virus in their blood. 



The author then proceeds to discuss the various methods of treating 

 animals attacked by ticks as follows : — Removal of the ticks by hand ; 

 Lounsbury's method, which consists in smearing the skin with a mixture 



