ADDIS0?<5 ON BLOOD-CORPUSCLES. 169 



ceptibility, those of different persons must differ to the 

 same^ prohably to a greater, extent. 



In correspondence with this inference, it is Avell known 

 that a number of persons may be inoculated with a poison, 

 or breathe at the same time an infectious atmosphere, but 

 only a few of them may take the specific or epidemic disease. 

 Tlie outbreak of smallpox fever in a particular individual is 

 dependent not upon what is in the air, nor upon the quan- 

 tity of virus inoculated, but upon some action in the blood 

 which the poison induces. If, upon breathing an infectious 

 air, or upon inoculation of a poison, no fever follows, the fact 

 is explained if the blood has resisted the poison. When a 

 poison fails to affect the person, it must have failed to affect 

 the blood. In smallpox, should the attack be slight, the 

 result would be so, if a majority of the elements of the blood 

 have resisted or escaped contagious action ; greater or less 

 severity in the symptoms denoting differences in the amount 

 of action in the blood. 



We are not compelled to conclude that smallpox virus 

 exists in the air when the disease occurs sporadically. On 

 the contrary, the presumption is, that the aerial miasm, the 

 action in the blood, and the matter of the pustules, are three 

 distinct things. 



There is, then, nothing in the history of siuullpox incom- 

 patible with the proposition that the red corpuscles of blood 

 are influential elements of the fever which precedes and 

 accompanies the regeneration of the smallpox virus. 



The necessity of distinguishing in pathology the fluid from 

 the corpuscles of blood is insisted upon, because diseases of 

 unwholesome diet are forms of local inflammation which 

 commence and go on without fever, viz., gout, scurvy, 

 diarrhoea, and eruptions; whereas, diseases of unwholesome 

 air are always fevers. 



All the cellular or parenchymatous elements of the body, 

 including the corpuscles of blood, have in various degrees 

 properties of resistance; and if, from unwholesome diet, me- 

 dicine, or poisons, local effects appear before or without fever, 

 it is because parenchymatous elements of the coats of the 

 vessels of the affected part are influenced by change in the 

 liquor sanguinis before the corpuscles of the blood. The 

 weakest resistance is the soonest overcome.^ But let us 

 continue the discussion with reference to other contagious 

 fevers. 



It must be conceded that the corpuscles of blood may be 



It t 



Giilstoniau Lectures,' 1859. 



