204 HOSACK ON THE LAWS OF CONTAGION. 



the vitiated atmosphere extends, in which they may be engendered, or 

 into which they may be introduced; and that, in this respect, they differ 

 from ordinary epidemics, " which appear in different and distant parts of 

 the same place, and at the same time." 



That the plague, when once generated, whatever may be the sources 

 whence it derives its origin, is communicated by a peculiar virus secre- 

 ted by the diseased body, will not, I trust, be questioned at this day. 

 Independently of the facts contained in the writings of Thucydides, 

 Lucretius, Mead, Dr. Patrick Russell, and others, showing the conta- 

 gious nature of the plague, the communication of this disease by 

 inoculation, as performed by Matthias Deggio,* Dr. Whyte,f and the 

 Russian surgeon, noticed by Sonnini,J have recently established the 

 fact of its propagation by a specific secretion, beyond all possible con- 

 troversy. 



It has been observed, by Assalini, that Dr. Desgenettes, while in 

 Syria, had in vain endeavoured to inoculate himself with the virus of 

 the plague ; and by the same writer it is incorrectly added, that Dr. 

 Desgenettes made the experiment under the persuasion that the disease 

 was not contagious ; but from the account of the facts as stated by Dr. 

 Desgenettes himself, it appears that the experiment was not made under 

 that persuasion. On the contrary, he expressly declares, that its conta- 

 giousness was demonstrated by a thousand examples, and observes, con- 

 trary to the opinion of many, that the same person was liable to a 

 second attack of it, as was the case with the convalescents whom he em- 

 ployed to attend upon the sick : furthermore it appears, from his own 

 account, that he inoculated himself with matter taken from a person who 



* See Med. Com. vol. 8. p. 349. f See Wilson's Expedition to Egypt, and M'Gregor's 



3ketches. $ See Travels into Greece and Turkey, p. 497. 



