CHEMICAL SCIENCE. 259 



the virus pervades the whole system, and the slightest wound is sufficient to 

 inoculate the complaint. 



You need not, however, he astonished at this singular property; you have 

 already witnessed the repulsion which the salivary glands evince for certain 

 substances introduced into the blood; and why should not certain morbid 

 principles be in this manner rejected from all the secretions in which the nor- 

 mal conditions remain unimpaired? The same thing appears to take place 

 with respect to the contagious pneumonia of horned cattle. We are aware 

 that volatile emanations transmit the morbid principle; but experiments 

 have been tried (in Belgium) for the purpose of inoculating it directly to ani- 

 mals, as a preservative against the disease. Something similar to the process 

 of inoculation in the small-pox was expected to result from this; it was then 

 discovered that neither the animal's blood nor any of the fluids of the econ- 

 omy was endowed with the property of propagating the complaint. It appears 

 to have chosen the lungs for its exclusive seat, and the liquids therein con- 

 tained, pus, lymph, etc., are alone endowed with the property of transmitting 

 the complaint. The intense local inflammation which follows the operation 

 sufficiently testifies to the noxious properties of this virus; and when, in order 

 not to spoil the animal's flesh, the tail is selected as the point where inocula- 

 tion is to be performed, the subsequent inflammation frequently causes it to 

 mortify. 



Here, then, we have another virus which exclusively resides in the tissues 

 of the lungs, and is not found in the blood at large; but even in the normal 

 state a great many substances are found in various tissues, which do not exist 

 in this fluid. Thus, muscular flesh contains a large amount of salts of potash, 

 while scarcely any trace of them is found in the blood; in a word, the vari- 

 ous bodies found in different parts of the economy are not invariably repre- 

 sented in the torrent of the circulation. 



The history of specific diseases offers, therefore, nothing which cannot 

 rationally be explained. It now remains for us to discover the physiological 

 progress by which a virus may be originated. Nothing is easier than to pro- 

 duce putrid affections in sound animals. Thus, when transfusion is per- 

 formed under the ordinary conditions, when the blood is conveyed directly 

 from one animal into the veins of another, no accidents whatever are pro- 

 duced; but if the blood is allowed to remain for a short space of time in 

 contact with the atmosphere, and if the serum is then injected into the 

 vessels, all the symptoms of putrid resorption are observed, and the ani- 

 mals die after exhibiting all the characteristic sjnnptoms of putrid infection. 



The blood is, therefore, capable of acquiring toxic properties without the 

 intervention of any foreign principle, merely through the modifications which 

 take place in its composition when life is extinct. The same results may be 

 attained to without even drawing blood from the veins. If the blood of a 

 fasting animal is directh r injected into the veins of a healthy one, the latter 

 is poisoned exactly in the same manner as before ; and yet the blood, in this 

 case, has not undergone any previous decomposition. 



The introduction of foreign principles, of course, acts upon the blood with 

 still more intensity; nearly all the substances known under the name of fer- 

 ments are endowed with the property of communicating a deleterious influ- 

 ence to this fluid. When yeast is introduced into an animal's veins, passive 

 hemorrhage, and other adynamic symptoms, are immediately produced, and 

 death takes place within a few days. Now, if the animal's blood is trans- 

 fused into another's veins, all the phenomena previously described take place 



