VETEEnvTARY MEDICINE. 585 



Ticks belonging to the same broods which had reached the nymph stage on 

 animals experimentally immunized against East Coast fever failed to transmit 

 the disease in 6 cases in the adult stage. This proves that brown ticks which 

 become infected in one stage are cleansed in the following stage whether they 

 engorged themselves on immune or susceptible animals. Ticks infected as 

 lai-vffi which passed the uymphal stage on a rabbit were not infective for sus- 

 ceptible animals as adults. This confirms the foregoing fact that a tick loses 

 its infection the first time it engorges on a susceptible or immune animal. 

 Clean or infected ticks which engorge on a recovered (immune) animal do not 

 transmit the disease in their next stage. This conclusion was arrived at 8 

 years ago [E. S. R., 17, p. 591]. 



" It has been shown that different broods of ticks which were collected at 

 the same time and kept under the same conditions do not transmit the disease 

 during the next stage even when placed upon animals in large numbers. Other 

 broods kept under the same conditions and collected in the same way infect a 

 few animals only, while still others prove to be infective on every occasion, and 

 even when used in small numbers only. It is difficult to explain this fact but 

 it is quite possible that external circumstances have an influence in some way 

 or other. Those ticks which failed to transmit the disease were fed during 

 the coldest periods of the year. This is possibly the explanation of the fact 

 that the disease in the field is relatively less severe during the winter months; 

 but the fact should not be lost sight of that at this period of the year the ticks 

 are not particularly active." 



Tick bite in British Columbia, J. L. Todd {Jour. Trop. Med. and Hyg. {Lon- 

 don^, 16 (1913), No. /,, pp. 58, 59).— This article relates to reports of cases in 

 which infection of the wouud caused by Dennacentor venustus had been fol- 

 lowed by local inflammation that was sometimes very severe; also of several 

 cases in which the bites of ticks have been followed by paralysis and sometimes 

 by death. The symptoms reported in these cases are said to be quite unlike 

 those that occur in Rocky Mountain spotted fever. 



The biology or life history of the cattle tick as determined at Auburn, Ala., 

 H. W. Gratbill and W. M. Lewallen (Alabama Col. 8ta. Bui. 171, pp. 75-06). — 

 The data here presented relating to the studies of the biology of the cattle tick 

 carried on at Auburn, Ala., during the years 1907 to 1909 have largely been 

 previously noted from another source (E. S. R., 25, p. 564). 



Dipping vats and dips, C. A. Cary {Alabama Col. Sta. Bui. 171, pp. 97-110, 

 figs^ S),— The author gives directions and plans for the construction of dipping 

 vats, directions for the use of the arsenical dip and of oil emulsion, with in- 

 structions for the taking up of the work of tick eradication. The regulations 

 governing shipment of live stock into Alabama are appended. 



Inquiry into dips and dipping in Natal, A. Theiler and C. E. Gray {Agr. 

 Jour. Union So. Africa, Jf {1912), No. 6, pp. 814-829; 5 {1913), Nos. 1, pp. 51-67, 

 figs. 9; 2, pp. 2^9-263) .—This article discusses at length the proper site and 

 construction of dipping tanks, including scale drawings. The effects of dips 

 upon animals are dealt with and practical advice given as to dipping various 

 animals, the question of cost being considered. 



In discussing the extent of tick infestation, it is stated that the area involved 

 was 1,144 square miles, or about one-eighteenth of the area of Natal. In some 

 instances the absence of ticks is thought to be due to the presence of the red- 

 beaked tick bird. 



Oxidation of the arsenite of soda in dipping tanks, C. Williams (Agr. 

 Jour. Union So. Africa, 5 {1913), No. 1, pp. 68-74 ) .—After summarizing the in- 

 vestigational work hitherto published on the subject, the author reports in detail 



