128 Bulletin 250. 



after another of the infected ones will be replaced with sound animals. 

 The goal toward which all are working is the eradication of bovine 

 tuberculosis as quickly as possible. 



8. Necessity of field experiments for the study of animal diseases. 



A careful review of our present knowledge of bovine tuberculosis 

 shows that, while we have many important facts concerning it, we still 

 need further information. This information can come only from actual 

 investigation on a considerable number of animals living under what 

 might be considered normal conditions. In order to know the best, or at 

 least the most economical, method of dealing with tuberculin-reacting 

 animals we need to have more knowledge concerning the recovery of the 

 slightly affected individuals and the conditions of the diseased processes 

 in the cases that fail to react on the second test. We have very definite 

 knowledge as to the means of dissemination and the channels of infection, 

 the course of the disease in the beginning and in the fatal cases, but much 

 additional knowledge of the -course of the disease in the arrested cases 

 that appear to recover is needed ; and much experimental knowledge must 

 be acquired concerning the best methods of handling such animals with 

 safety to themselves and to others. Vaccination or immunization of cattle 

 against tuberculosis is now being strongly advocated, but before our cattle 

 owners accept such recommendations they should be assured by carefully 

 conducted experiments that the methods are genuine and that the results 

 will be satisfactory. 



The millions of dollars invested in cattle in New York State and the 

 importance of the cattle industry to the general welfare of the State, 

 demand that no effort should be spared to secure the most perfect knowl- 

 edge of tuberculosis and also of other infectious and communicable animal 

 diseases. From the very nature of the case this information cannot be 

 forthcoming without ample opportunities for investigation. We must 

 supplement the laboratory and stable work with actual field work on a 

 farm or farms that are devoted to these particular purposes. 



Veranus a. Moore. 



