228 DEPARTMENTAL EEPORTS. 



that the cattle exposed to Porto Rieaii ticks suffered an attack of 

 Texas fever too mild to be diagnosed as the result of the exposure ; 

 and, second, that the mild disease was sufficient to produce such 

 changes in their blood that they were capable later on of reinfecting 

 noninfectious ticks with an infection sulhciently virulent to cause 

 fatal Texas fever. The ticks referred to as Porto Rican ticks are 

 identical with the well-known Southern cattle tick. A further report 

 on this sul)ject will be presented at another time. 



A number of other experiments concerning Texas fever were planned 

 for the year, but could not be made because of the lack of space and 

 time at the station. 



The Soutliern cattle tick dip question remains without a wholly sat- 

 isfactory solution. Many dips were tested during the year and were 

 found to be unsatisfactory. The dips either do not kill the ticks or 

 affect the cattle too severely to be of practical value. The ticks show 

 a wonderful resistance to adverse conditions which is entirely out of 

 proportion with their small size. Among the dips tested, the best 

 results were obtained from the so-called Australian dij), which has the 

 following formula : 



Stockholm tar gallons.- 7| 



Carbonate of soda pounds.. 23 



White arsenic ...... do 8 



Water sufficient to make 400 gallons. 



This dip is objectionable because of the arsenic which it contains 

 and because it is necessary to dip an animal twice before all the ticks 

 are killed. From the first dipping the cattle do not seem to suffer 

 much, but as a result of the second dipping it has been frequently 

 noticed that they refuse food for several days, act generallj^ depressed, 

 and have a more or less severe diarrhea. The same dip without 

 arsenic at one trial gave very encouraging results, but when tried 

 again, prepared with tar from another barrel, it proved to be almost 

 without effect on the ticks. 



A number of modifications of the Australian dip have also been 

 tried, such as an increase in the amount of tar, the sulxstitution of 

 North Carolina tar for Stockholm tar, the substitution of other alka- 

 lies for the carbonate of soda, the addition of soap, etc. No better 

 results were obtained. Tlie addition of soap to the Australian dip 

 containing arsenic killed practically all the ticks, but also killed two 

 of the three cattle dipi^ed. Dips containing as the main ingredients 

 carbolic acid, tobacco extract, oil, sodium sulphate, glycerine, lime, 

 and sulphur, and numerous other substances, either singly or in com- 

 bination, have been tried and found to be unsatisfactory. This work 

 is still in progress and will be continued. Possibly something may be 

 done by combining- a dip with a drench containing substances which 

 will act on the tick through the secretions of the skin of the cattle. 



THE DAIRY DIVISION. 



The general survey of the condition of the dairy industry of the 

 United States, begun upon the or4>:anization of the dairy division, has 

 been continued, and special inquiries have been made along lines such 

 as the milk supply of cities and towns and the development of foreign 

 markets for our butter. Some reports have been issued and others 

 are nearing completion. 



The routine work of the office, including preparation of manuscripts 

 for publication and replying to the requests for specific information 



