36 THE HISTORY, NATURE, SYMPTOMS, AND 



The spontaneous generation of this and other contagious 

 diseases is a subject that is being investigated at the present 

 time by eminent and scientific medical men, but as yet 

 their conclusioDs are far from being unanimous; the majority, 

 however, incline to the belief that spontaneous generation is 

 impossible. Dr. Budd, in writing to the Medical Times in 1864, 

 says : — " I have myself come to the conclusion that there is no 

 proof whatever that they ever do so. That the evidence, in fact, 

 on wdiich the contrary conclusion is founded, is negative only ; 

 that evidence of precisely the same order, only to all appearance 

 still more cogent, would prove animals and plants, even of large 

 species, to originate spontaneously ; that this evidence is there- 

 fore of no weight ; and, lastly, that as in the case of plants and 

 animals all the really important facts point the other way, and 

 tend to prove that these poisons (to use a word that is probably 

 provisional yet), like plants and animals, however they may have 

 once originated, are only propagated now by the law of con- 

 tinuous succession." 



The nature of the viruliferous agent has not yet been clearly 

 demonstrated. There are records of some very interesting 

 experiments and numerous investigations, but no definite 

 decision has been arrived at as to what is really the character 

 of the virus. Various theories have been propounded, such as 

 bacteria, parasitism, and fermentation. Even w4th the aid of 

 the microscope much remains to be done to bring practical facts 

 and the various theoretical vie^vs into harmopy, and never can 

 veterinary science and medicine prevent and control the spread 

 of contagious diseases till we can thoroughly grapple wdth, and 

 understand the intimate nature of the contagious element. Dr. 

 Beale, in his work on Disease Germs ; their Real Nature^ on this 

 point says: — "The materies morbi of contagious diseases does 

 not consist of lifeless organic matter or inorganic matter, nor of 

 any form of gas or vapour generated in the decomposition of 

 animal or vegetable substances, nor by any matter set free during 

 the decomposition of faecal or other excrementitious matter of 

 animal origin. Xor is it any species of animal or vegetable 

 organism or parasite ; but the active contagious material con- 

 sists of exceedingly minute particles of living germinal matter, 

 which may be regarded as the direct descendants of the germinal 

 or livim::^ matter of an ornjanism which has been for some time 

 living under unusual conditions. Contagious poisons affecting 

 man and animals ori2[iuated in their oro-anisms. The living or 

 germinal matter of some contagious diseases originating in the 

 bodies of animals may grow and multiply in man and vice xersa. 

 . . . The smallest particle (less than the hundredth-thousand 

 part of an inch in diameter) being introduced into the body, 

 already in a fit state for its nutrition, may grow and multiply, 



