Lung Plag2ie in Cattle. 621 



awning to keep off dust. The space soon fills with the draining 

 exudate in a very pure condition. 



Pasteur inoculated a calf in the dewlap or behind the elbow, 

 where an enormous engorgement forms, involving the whole ven- 

 tral aspect, and supplying an almost unlimited amount of serum, 

 which may be collected with such precautions against contamina- 

 tion as are indicated above. The product is thus secured at a 

 comparatively cheap rate, and the risk of its diffusion on the air 

 in breathing is lessened enormously. 



Another method is to employ the serum from the swellings in 

 the inoculated tails and carry it on indefinitely from tail to tail. 



Arloing in his turn employed the cultures in vitro of his pneu- 

 mo-bacillus, but with the modern evidence that this is not the 

 infective germ, such cultures can not always be implicitly relied 

 on. 



In place of the hypodermic syringe, Australians have used a 

 simple thread soaked in the exudate and drawn through beneath 

 the skin. Others have used a small lancet with a groove hollowed 

 out in the middle of the flat surface of the blade on one side, and 

 which carries in the required drop of the serum. 



To preserve the exudate for some time against decomposition, 

 it has been kept on ice, or mixed with chloral hydrate or phenic 

 acid (*4 its volume), and glycerine (}4 its volume) for two or 

 three months. 



Injection into the veins practiced by Burdon-Sanderson has the 

 advantage of producing no local lesion whatever and yet securing 

 a fair measure of immunity. It is, however, a much more deli- 

 cate operation as it entails a possible though remote possibility of 

 producing capillary thrombi, and some danger of infection of the 

 wound in the vein. To avoid this latter, the jugular vein is 

 raised as for phlebotomy, and a short needle is passed into it. A 

 longer and more delicate needle is now passed through this, and 

 the injection of a few drops of the exudate is made through the 

 latter. The small needle is then carefully withdrawn to be 

 followed a few seconds later by the large. 



Injection of the Sterilized Exudate Subcutem. In 1881 having- 

 found that liquids obtained from old sequestra, produced no local 

 lesions when inoculated subcutem, but secured immunity for the 

 subjects. I inoculated ten susceptible cattle with the fresh pul- 



