990 LIVE STOCK AXD BREEDING 



rum and red globules) are used in the same way as with the products of 

 local lesions. The best method for preserving its virulence and observing 

 its infective power in those tissues where the disease arises preferentially 

 under natural conditions, is that of inoculating into the tongue infective 

 material or blood taken from the animal during a period of fever excee 

 ding 400 C, or the product of local lesions. The maximum virulence is 

 produced by passing through the epithelium of the digestive apparatus 

 (tongue or paunch). 



2) The virus obtained in this way, whether fixed or temporary, 

 represents the maximum intensity of virulence both in infective and spread- 

 ing power, the adult animal falling sick in 24 to 36 hours. It almost al- 

 ways kills young animals, especially when not yet weaned (calves, lambs, 

 kids or sucking pigs), by general infection, the virus being constantly present 

 in the blood. 



3) The present experiments wordd appear to show that several kinds 

 of animals are capable of containing in their blood for some time a very 

 virulent virus of foot-and-mouth disease, without specific external symptoms 

 or with merely slight lesions of the mucous membrane of the digestive ap- 

 paratus or the pad of the short pastern. 



4) With the blood products kept in a thermostat, or cold, until the 

 virulence is exhausted, it is possible to create a resistance to foot-and-mouth 

 disease in animals, which will allow of making successive inoculations of 

 li\nrg virus, and of obtaining a much higher degree of immunity as compared 

 with animals which have overcome the disease in a serious form (38 months 

 of observations on a group of 20 cattle). 



5) Similarly it is found that the serum of the blood of cattle which 

 have passed beyond the febrile stage of the disease is of marked curative 

 and preventive efficacy against even a malignant form of virus. The in- 

 oculation of the blood as such or of serum, under these conditions (containing 

 the maximum of antibodies), is a sure preventive of the death of adult ani- 

 mals, and results in their speedy recover}-. A therapeutic system in the 

 cowshed or cattle-pen is therefore practically possible, if serum be taken 

 from recently cured animals and injected into those most seriously ill. In 

 this connection, the haemovaccination advocated by Perroncito also poss- 

 esses an acceptable pratical basis. 



6) In foot-and m^outh disease, 2 forms of immunity are distinguish- 

 ed, one general, which is located in the blood and more particularly in the 

 white globules (pref erentialty eosinophiles) , the red globules and the plasma; 

 the other of a more strictly histogenic character and involving the protec- 

 tive epithelia of the digestive passages. The latter is less lasting than the 

 immunity located in the blood, and is strictly related to the wear and re- 

 generation of the epithelial cells. In cattle, by means of injection into 

 the tongue, it is found that the gradual loss of immunity begins with the 

 epithelium of the tongue, followed by that of the rumen and the small intestine, 

 and the mucous membrane of the hoof pad. 



Thus, as happens under natural conditions, there may be animals pre- 

 senting serious external symptoms, involving chiefly the epithelium of the 



