178 THE AMERICAN MONTHLY [Oct. 



curing sick hogs and of preventing well ones from be- 

 coming infected. Unless the blood is to be used imme- 

 diately after it is drawn, which is not often the case, it is 

 allowed to coagulate or clot, and the liquid portion, or 

 serum, is separated and preserved for future use. 



The Agricultural Department has been diligently work- 

 ing for several years to bring the serum treatment of hog 

 cholera to the highest degree of efficiency. The most im- 

 portant point is, of course, to secure a serum with high 

 protective and curative power. This is by no means an 

 easy task. The products of the hog cholera germ are 

 irritating, and when injected into the tissues their ten- 

 dency is to cause paralysis and death of the part, with 

 the formation of large abscesi:*es. The intense local 

 action hinders the absorption of the cultures into the gen- 

 eral circulation and prevents the animal from acquiring 

 immunity. It is doubtless for this reason that the inocu- 

 lation of swine has generally failed to give the necessary 

 degree of protection and that inoculated swine are found 

 to contract cholera when they are afterwards exposed. 



The serum produced in 1897, when used in affected 

 herds, saved over 80 per cent of the animals. The 

 methods have been considerably improved, and it appears 

 proable that a serum (5f higher eflBciency will be the re- 

 sult. There is no danger connected with the use of this 

 serum, as it is absolutely free from the germs of the 

 disease. It is easily applied, and the good effects in sick 

 hogs are seen almost immediately. There is every reason 

 to believe, therefore, that we have in this serum a prac- 

 ticable method of preventing th»i greater part of the 

 losses from hog cholera, but it must be tested upon a 

 larger scale before absolute assurance can begiven. — Re- 

 port of Bureau of Animal Industry. 



■Wolle's Diatomacese of North America with plates for 

 ^ale cheap. Address the Editor. 



