235 



mosquitos in France seem to be the existence of low, isolated habita- 

 tions built at ground level in the midst of a moist wooded or swampy 

 zone. Such conditions of Ufe, which are primitive, have become 

 exceptional in France, but have been renewed during the war by the 

 estabhshment of camps and more or less permanent buildings within 

 the zone of flight of mosquitos. In this way there have arisen, and 

 will still arise under the influence of a fresh introduction of the virus, 

 small foci of locally acquired malaria. This invasion by man of the 

 zones of flight of Anophelines will cease with the War, and then 

 these temporary centres of endemic malaria will automatically become 

 extinct. 



It is obvious from the foregoing that the presence of Anophelines 

 without malaria in France is explained by the organisation of human 

 settlements outside the zones of flight of Anophelines, and it is equally 

 clear that malaria can be controlled, at least in temperate chmates, by 

 the simple precautions necessary for the prevention of continued 

 intimacy of hfe between man and Anophehnes, without attempting 

 the complete destruction of the latter. Further knowledge of the 

 biology of Anophelines will be necessary in order to reach a definite 

 understanding of the conditions capable of encouraging or suspending 

 the relations between mosquitos and man. 



Abridged Report of the Chief Veterinary Surgeon for the Year 1917. — 



Rhodesia Agric. Jl., Salisbury, xv, no. 4, August 1918, 

 pp. 339-343. 



Thirteen fresh outbreaks of African coast fever were reported 

 during the year. It is realised that without ticks there would be no 

 coast fever, but under local conditions the complete eradication of 

 ticks is considered impossible, though the complete elimination of 

 infection is possible. If every area carrying infected ticks could be 

 accurately defined the disease could be eradicated within two years 

 by present methods. In the majority of cases, however, the disease 

 has been in existence for several months before it is brought to notice 

 and meantime infection has been disseminated, which is not manifest 

 for another extended period, and so the disease is always ahead of the 

 control. To remedy this state of affairs universal compulsory dipping 

 of cattle throughout the Territory has been proposed. Whilst the 

 value of this method is fully appreciated, it is stated that weekly 

 dipping, however efficiently practised, will neither eradicate coast 

 fever nor prevent its spread. While dipping reduces the number of 

 ticks, it also serves to mask the disease for an indefinite period, with 

 the result that recrudescences occur where the disease was regarded 

 as stamped out and fresh outbreaks occur on previously clean areas. 



Hirst (S.). On Four New Species of the Genus Demodex, Owen.— 

 Ann. Mag. Nat. Hist., London, (9) ii, no. 8, August 1918, 

 pp. 145-146. 



The four new species dealt with are : — Demodex soricinus, sp. n., 

 from Sorex vulgaris ; D. apodemi, sp. n. , and D. longior, sp. n. , from 

 Apodemus sylvaticus ; and D. nanus, sp. n., from Rattus rattus (black 

 rat). 



