468 Observations on Inoculation loith the Virus of 



temperature does not rise, the appetite continues good, and the 

 secretions are not affected. 



The Question of the Protective Effects of Inoculation 



considered. 



Arguing solely on the basis of the evidence which has been 

 ■adduced of the action of the virus of pleuro-pneumonia on healthy 

 animals, it cannot be logically assumed that inoculation with the 

 morbid products of that disease will protect the system from a 

 natural attack, because the one essential condition on which the 

 success of inoculation in all other contagious diseases of stock 

 depends is not present. 



Contagious lung disease does not follow the introduction of 

 the so-called virus into the organism of a healthy animal. No- 

 thing short of association with living diseased cattle suffices to 

 induce the affection, so far as experiments have yet been con- 

 • ducted. This fact is brought prominently forward in the Report 

 from the Royal Veterinary College, published in the present 

 number of the ' Journal.' The details of various important ex- 

 periments are given in that Report, and it will not be necessary 

 to repeat them here ; but, for the purpose of the argument, refer- 

 ence may be made to the chief points which are there dis- 

 cussed. 



In the earlier experiments, exposure of healthy cattle to con- 

 tact with the diseased lungs, and the introduction of a sponge 

 into the nostrils immediately after its removal from the nostrils 

 of a cow affected with pleuro-pneumonia, failed to produce the 

 disease. More recently the fluid exuded from diseased lungs was 

 injected into the circulation, into the bronchial tubes, and into 

 the lung tissues of healthy animals. In two cases fatal effects were 

 produced, but no signs of disease of the lungs were present. 

 Extensive exudation of serum, with abundant granular deposit, 

 •occurred in these instances, but only into the subcutaneous areolar 

 membrane and the superficial muscles. The one remarkable 

 feature was the absence of any signs of disturbance for periods 

 Tarying from fourteen to twenty-one days. 



Injection of the virus into the circulation produced no result. 

 The introduction of a small quantity of the exudate into the 

 stomach of a calf caused death in a few days from blood-poisoning, 

 without exciting any disease in the lungs. When local disease 

 ^becomes severe, as it did in some of the cases referred to, and 

 as it does in some instances when inoculation is performed in the 

 usual way, symptomatic fever is indicated by rise of internal 

 temperature and other characteristic signs, which differ in no way 

 from the symptoms of fever resulting from a severe injury of an 



