180 EXPERIMENT STATION EECOED. 



lesions, thf iiiiiforin dislrihutioii of i)Mtclifs tliroujilioiil llic liver, ami tlio rela- 

 tion between certain lieniorrliaj;es and the divisions of tbe portal cirenlation 

 suggest that the causative agent is carried by these venous channels; this cause 

 is a toxic princiiile. either present in the food or of microbic character, more in 

 our opinion due to microbes which produce a change in the tone of the capilla- 

 ries and favors their walls yielding under the influence of blood pressure. 



" This latter manner seems to us more probable. One liuows that temporary 

 attacks of enteritis, whiclj are much more common in animals that are overfed, 

 such as milch cows, have a well-marked action on the liver in consequence of 

 the absorption of toxins or of microbes. 



" We can not say that the agent isolated by us has any etiological role what- 

 ever, experimentation being nearly impossible from this point of view. In 

 regard to the inspection of meat we believe that one can without danger con- 

 sume the livers unless they show general change; those which have undergone 

 marked change should be destroyed." 



Hemorrhag-ic septicemia or pasteurellosis of cattle, F. Hutchinson {Natal 

 Agr. Jour., 11 {1908). No. 12, pp. 153.'f-lo39).— This is a general account of the 

 disease in which the results of a i)ost-mortem examination of an affected cow 

 are included. 



A practical dem.onstration of a method for controlling' the cattle tick, 

 W. D. Hunter and J. D. Mitchell {U. *s'. Dcpt. Agr.. Bar. Aniiit. Indus. Circ. 

 L'lS. pp. .'/). — This circular deals with a demonstration of a method for con- 

 trolling the cattle tick that was carried out by the Bureau of Entomology of 

 this Department under practical conditions. The ob.iect of this demonstration 

 was not so much to exterminate the tick as to bring it under control and avoid 

 as far as possible the heavy expense of dipping cattle. 



In a pasture of about 30.000 acres located in the northeastern portion of Vic- 

 toria County, Texas, an area of about 1 mile square was fenced off, the most 

 brushy and. according to the owner, the most " ticky " part being purposely 

 chosen. On the completion of the fence. July 25, 1907, the cattle were all 

 removed and rigidly excluded until December 12 — that is, 140 days later. From 

 the herd in the main pasture 65 head were then taken at random, dipped in a 

 vat filled with a proprietary " tickicide," and placed in the demonstration 

 pasture, there remaining undisturbed through the winter. In an examination 

 of the cattle on June 2G a total of 7 ticks were found on 4 animals. These are 

 supposed to have been the progeny of individuals w'hich dropped from the out- 

 side cattle near the fence. 



In order to determine the longevity of the progeny under favoral)le conditions, 

 engorged ticks were placed in glass tubes about the time of the removal of the 

 cattle from the demonstration pasture, August 1. The seed ticks were all found 

 to be dead 120 days after the engorged ticks were placed in the tubes. 



It is believed that equally successful results, can be obtained by any cattle 

 raiser in the South from the methods used in this demonstration with slight 

 modifications. 



The Natal spraying device, H. Watkins-Pitchfokd {Natal Agr. Jour., 11 

 (1908), Ns. 12, pp. 1576-1580, pis. 3). — The author presents plans and photo- 

 graphs of a spraying device for use in destroying ticks and other ectoparasites. 

 While the merit of portability can not be claimed for this device, it is simple of 

 construction. 



Poisoning' from gnat bites, P. Wigand {Berlin. Tieriirtztl. Wchnschr., 

 1908, No. 48, pp. 858, 859; abs. in Jour. Compar. Path, and Titer., 22 {1909), No. 

 1, pp. 5/f-56). — During the past 10 years 2 species of gnats, Simiilium reptana 

 and /S'. ornata, have attracted attention among breeders and veterinary sur- 

 geons. Recently they have appeared in enormous numbers and caused exten- 



