252 ANNUAL nrroRTs of department of agriculture. 



veterinary dopartinent of the Aluhiiina Polyteclinic Institute, was 

 issiunl (luiin*; the year. 



In oxporiinents with arsiMiical (hps it was found that no ai)f)recial)le 

 ill ellcots were produced on calves dipned during the period from the 

 latter part of June to the latter part of Octoher, repeated at intervals 

 of two and three weeks in a dip composed of 10 pounds of arsenic 

 trioxiil, 25 pounds of sodium carhonate, 1 gallon of j)ine tar, and 500 

 gallons of water. 



Two series of experiments were conducted with a proprietary 

 arsenical dij). one durinjj; the summer in southern Texas, the other 

 durin<; the fall in ( )klahoma. The dij) proved ellicacious in destroying 

 ticks when applied twice with an interval of 10 days between dip- 

 pmgs and at a dilution which gave an equivalent of 0.22 per cent 

 arsenic trioxid in the dipping ])ath. 



Experimer.ts on a small scale with an arsenical dij) prepared in 

 concentrated form by the Biochemic Division were sulliciently favor- 

 able to warrant field trials of the preparation. 



In all of the experimental work with dips, the Biochemic Division 

 has cooperated in devising improvements in the preparation of the 

 dips and in supplying analyses of the dips used. 



Investigations have been begun in cooperation with the Biochemic 

 Division relative to the absorj)tion of arsenic through the skin of 

 cattle dipped in arsenical dips and the effect of such absorption upon 

 cattle and upon subsequent tick infestation. 



INVESTIGATIONS CONCERNING PARASITIC PROTOZOA. 



Further work has been done upon a trypanosome common in the 

 blood of American cattle, but apparently nonpatho<i;enic, and a 

 bulletin recording this work has been prepared for pubhcation. 



Interesting and important facts have been determined relative to 

 certain morj^hological details in the Sarcosporidia. 



Fortunately for the live-stock industry of the United States, no 

 exotic trypanosome disease has succeeded in becoming established 

 in this country, although animals as stock and for menafreries have 

 been brought here in the past more or less indiscriminately from all 

 parts of the world. Past good fortune, however, does not necessarily 

 promise immunity for the future. As illustrations, it may be noted 

 that importation of animals from Europe went on for several hundred 

 years before that highly injurious pest of live stock, the horn fly, 

 became established (since 1886) in this country, and that dourine 

 was brought in only a few years ago, the first outbreak causing con- 

 siderable damage before the disease was eradicated. It is therefore 

 highly important that all possible practicable precautions should be 

 taken to guard against the ever imminent danger of introducing 

 trypanosome diseases with shipments of animals from abroad, espec- 

 ially in view of the fact that these diseases, as a rule (dourine bei^g 

 as cxcej)tion), are transmitted by winged insects and hence are almost 

 impossible to eradicate if they become established. In order to 

 supply information relative to trypanosomes, in a readily available 

 form, a paper is in preparation, and nearing completion, in which are 

 given the diagnostic characters, life history, host animals, and geo- 

 graphic distribution of all known species of trypanosomes. 



