70 FOURTH REPORT 1834. 



long voyage in a ship, the hold of which was densely crammed 

 with swine and sheep arranged on different sides of the vessel, 

 Dr. Fordyce observed that both those kinds of animals were at 

 different times attacked with contagious fevers, the symptoms 

 varying in the two species, and the disease not spreading from 

 the one species to the other, nor at all affecting the passengers 

 or crew*. 



III. Independently of crowding and confinement, contagious 

 fevers do, however, occasionally arise without any immediate 

 prototype. The recollection of every medical practitioner must 

 furnish examples in which simple fevers, arising from cold and 

 other causes, in persons well fed and well clad, have by neglect 

 become contagious in their progress ; and if particular examples 

 of this kind are seldom recorded, it is because of the notoriety 

 of the general fact. An instance of typhus fever, thus origina- 

 ting spontaneously, is related to have happened to one of the 

 family of the late Dr. Jennerf. 



IV. Diseases which break out in a scattered manner, where 

 the agency of contagion can neither be traced nor even suspected, 

 have been called sporadic (from o-Tropaj, sparsus). This class 

 therefore includes all disorders that are not produced by conta- 

 gion ; nor by accidents or obvious injuries ; nor by any cause 

 affecting numbers of individuals in common. 



V. There is an extensive class of acute diseases, which have 

 never yet been proved to arise sporadically . These, from 

 the greater distinctness and more uniform succession of their 

 symptoms, have been considered as separate species. They 

 have therefore been termed specffic diseases, and their causes 

 SPECIFIC CONTAGIONS, or SPECIFIC INFECTIONS. Such are 

 siphylis, measles, smallpox, cowpox, hooping-cough, scarla- 

 tina, and a few others. 



VI. In a great proportion of instances, specific diseases may 

 be traced to communication, either by contact or near proxi- 

 mity, or intermediately, with some person suffering under the 

 same disease. But it frequently happens that the most search- 

 ing and diligent inquiry fails to trace a specific disease to its 

 source. We are told that not one in twenty cases admitted into 

 the Smallpox Hospital in London could be referred to any im- 

 mediate original J. In a few instances, specific diseases have 

 appeared within boundaries which might have been supposed to 

 liave perfectly excluded them. In the Penitentiary at Millbank,- 

 a prisoner was seized with smallpox, notwithstanding his ap- 



* First Dissertation on Fever, p. 112. 



f Baron's Life of Jenner, p. 106. 



X Dr. Gregory, Cholera Gazette, No. 2. 



