258 ANNUAL OF SCIENTIFIC DISCOVERY. 



to preserve it from contagious diseases, we must increase them by all possible 

 means. 



But these septic bodies, or specific poisons, are almost invariably organic 

 substances, and are produced within a living organization; here we have, no 

 doubt, a peculiar and characteristic biological action; we need not, there- 

 fore, be surprised to see pathologists endeavoring to withdraw this class of 

 phenomena from the domain of physiology, in order to make them the 

 exclusive property of medicine. 



We must not, however, in my opinion, give up all hope of connecting, 

 one day, these morbid phenomena with the laws of physiology. If at 

 present unable to do so, we shall, no doubt, succeed at some future period. 

 Is it not, in fact, quite possible that in animals certain physiological con- 

 ditions may arise which would give birth to virulent poisons? We are 

 aware that in a perfect state of health several creatures are venomous; 

 that is to say, they possess a peculiar virus which nature has given them for 

 the purpose of killing their prey and defending themselves from their 

 enemies. Here, then, we have a physiological virus; how is it produced 

 within the system ? The difficulty is quite as great as with regard to morbid 

 poisons. 



It would appear that in several cases the noxious substance prevails 

 throughout the economy; in other cases, we only discover it in certain 

 fluids. The virus which occasions hydrophobia belongs to the latter class-; 

 it resides exclusively in the animal's saliva. We are not yet aware whether 

 any one of the salivary glands is its peculiar seat, or whether it is indiffer- 

 ently secreted by all of them. No experiments have been tried on this 

 point; but it has been experimentally proved that the peculiar venomous 

 principle does not exist in the blood; transfusion does not convey the disease 

 from a mad dog to a healthy one. 



It is a singular fact, and one which preeminently deserves our attention, 

 that in so general a disease the virus, which alone is capable of transmitting 

 the affection, should be exclusively localized within one single apparatus, 

 without existing in the blood at large. Yet, if we reflect upon the question, 

 we discover in the phj'siological state a great many similar dispositions; the 

 principles which concur in a vast number of physiological functions, pepsin, 

 ptj'aline, and the active principle of the pancreatic juice, are they not created 

 by special glands? And is not the venom of serpents, which does not exist 

 within the blood, produced by a special apparatus? Viewed in this light, a 

 mad dog resembles a viper or a rattlesnake. 



But, on the other hand, there exist several virulent diseases in which the 

 blood really appears to contain the morbid principle. This is the case with 

 the glanders ; and it is a well-known fact that healthy animals may be infected 

 with the blood of a diseased horse, as well as with the slimy matter that 

 escapes from the nose and mouth. 



But another particular which will, perhaps, excite your astonishment, is 

 that the normal secretions, bile, saliva, gastric juice, and so forth, do not 

 appear to contain the slightest vestige of this poison ; while, on the other 

 hand, the pathological fluids appear to be impregnated with it, and possess 

 the property of transmitting the disease to sound animals, a fact experi- 

 mentally proved with regard to pus, the fluid contained in a hydrocele, and 

 various other morbid secretions. For this reason alone are the autopsies per- 

 formed on animals that die of the glanders attended with so much danger; 



