112 



A fourth species — T. simiae — causes disease in pigs. It is con- 

 ceivable that it may be only a variety of T. congolense modified by 

 passage through the warthog. 



Rice Culture and Malaria. — California State Bd. Health Mthly. Bull, 

 Sacramento, xv, no. 8, February 1919, p. 270. 



Owing to the increase in rice cultivation in California, the malaria 

 problem will require greater consideration ; for this reason special 

 work is to be undertaken in the eradication of mosquitos from the 

 cultivated districts. 



Johnson (T. H.) & Bancroft (M. J.). Report on Mr. Munro Hull's 

 Claims regarding Ticlj-resisting Cattle.— Queensland Agric. Jl. 

 Brisbane, xi, no. 1, January 1919, pp. 31-35. 



The question of the tick resistance of cattle has been investigated 

 by the authors during the years 1915-1918, special attention having 

 been given to the animals forming part of Mr. Hull's herd, concerning 

 which the latter put forward certain claims in 1912. He maintained 

 (1) that on these cattle only a few female ticks (50 to 100) mature 

 in the year, though they are regularly (naturally) infested by mjTiads 

 of larvae ; (2) that they do not require any attention as regards ticks, 

 and may be turned out on any country for indefinite periods without 

 experiencing tick worry ; (3) that this peculiarity is transmissible to 

 other cattle by contact and by vaccination and is always transmitted 

 to their progeny, in which, however, it does not manifest itself untU 

 after the first year of life ; (4) that the material used for vaccination 

 (the exudate on the escutcheon of resistant stock) does not result 

 from excessive tick worry ; (5) that the few female ticks found maturing 

 on such animals have been displaced without injury from other cattle 

 and have re-attached themselves to the resistant stock ; (6) that though 

 these ticks oviposit, no larvae develop ; (7) that a few ticks are to be 

 found on such animals at odd times during winter when other cattle 

 are free from them ; (8) that such cattle have a markedly higher 

 temperature during winter. 



In 1914 Mr. C. J. Pound, as a result of his observations regarding 

 two tick-resistant cows purchased by the Government, reported ad- 

 versely on the above claims, disagreeing with every point. 



In 1915 Mr. Hull again restated his claims, and, as a result of further 

 observations, modified certain of them, as follows : — The number 

 mentioned under point (1), was in many cases underestimated, many 

 of the minute ticks continuing to develop but dying before engorge- 

 ment ; that certain cases of transmission of resistance (3) are really 

 due to contact ; and that in one case the exudate appeared on a calf 

 during the first year of life. 



In 1918 one of the authors made a detailed study of Mr. Hull's 

 cattle for a prolonged period, during January, February, March and 

 June, when all the engorged ticks to be found on resistant animals 

 were carefully collected, most of the cattle being inspected twice 

 daily, and the non-milkers once daily. A thorough collection from 

 9 supposed resistant cows during a period of 27 days at the height 

 of the tick season yielded only 13 fully matured ticks, though control 



