142 ESSENTIALS OF VETERINARY LAW 



spread by the overflowing of pastures by streams 

 which received the discharge of tanneries in which 

 infected hides had been treated.^'^ Reasonable 

 quarantine there might therefore include the pro- 

 hibition of the use of such pastures. Dourine was 

 formerly supposed to be spread only by inter- 

 course, and under such conditions quarantine 

 would only prevent such relations between the 

 healthy and the sick. The experiments on the 

 Canal Zone, however, showed that the disease may 

 be spread by flies. A reasonable quarantine of 

 many animal diseases must include screening 

 against insects. All that is necessary and efficient 

 will be sustained; nothing in excess of that would 

 be approved by the courts, in most instances; but 

 in deciding what shall, and what shall not, be sus- 

 tained the courts will be guided not only by past 

 usage, but also by scientific advances when 

 properly presented. It is necessary that the 

 officer presenting some new method for the con- 

 sideration of the court remember that his own 

 bare statement of fact may not be enough; he 

 may be obliged to say how his position in opin- 

 ion has been gained. It may not be enough to say 

 that yellow fever is only transmitted by the bite 

 of the stegomyia, but the officer should state how 

 that fact has been demonstrated ; and the necessity 

 for such presentation is in direct ratio to the new- 

 ness of the demonstration. 



A state statute in "Wyoming directed the state 

 veterinarian to quarantine for certain diseases; 

 and it further gave him authority to order infected 



2T Bavenel, Eept. Am. Pub. sell, Eept. Wis. Agr, Expt. Sta- 

 Health Assn., 1898, p. 302; Eus- tion, 1900, p. 171. 



