150 PARASITICAL GROWTHS ON LIVING ANIMALS. 



These are the principal facts which I have been able to collect on this 

 subject ; for it is scarcely worth while to refer to the vague speculations 

 of M. Meynier of Orleans, whose assertion of the analogy of warts and 

 similar growths, with Fungi of the order Gymnospermia ; of Lepra and 

 Psoriasis with Lichens and Mosses ; and of pulmonary tubercle with 

 Lycoperdon, may, I think, justly be considered more the fruit of a heated 

 imagination than of sure observation. The Mucores observed by Langen- 

 beckin the body of a person dead of typhus, had certainly no connection 

 with that disease ; and, as for the opinion, that hospital gangrene is 

 dependent on the presence of a fungoid growth, I am unable to refer to 

 the authority, upon which such a doubtful statement is founded. 



The above briefly recited facts are far too few in number, and not 

 sufficiently precise, to allow of any general deductions of importance to 

 be drawn from them ; but it appears clear, 



1 . That parasitical growths occur in nearly all classes of the animal 

 kingdom. 



2. That these growths arise usually on the surfaces of animal organs, 

 and are sometimes prolonged thence into the textures of the part. 



3. That they have in several instances been ascertained to constitute 

 the cause of disease and death ; and that the disease thus produced has 

 been found in some cases to be contagious. 



4. That they are probably of two kinds, the one peculiar to animal 

 bodies, and the other consisting of these Cryptogamic vegetations, which 

 readily sprout up under favourable circumstances, on almost any inani- 

 mate substance. 



To the former kind may be referred the Muscardine of the silk- worm 

 and Mycoderm of Tinea ; and to the latter, most of the other growths 

 above alluded to.* 



The vegetable nature of these growths does not in all cases appear 

 so clear as might be supposed. In some of the instances cited above, 

 there can be no doubt on the matter ; but in others, and especially that 

 of the Mycoderm, constituting the crusts of Tinea, it is allowable to 

 doubt whether the growth may not be more properly referred to the 

 animal kingdom. In fact, it would appear, from the chemical consti- 



* With the exception of the Parroquet, whose case is related by M. Rousseau 

 and M. Serrurier, in which, in the account given by these observers, the seat of 

 the parasitic growth is by no means clearly defined, it would appear that these 

 parasitic growths have nearly all had some relation to the air passages, and in this 

 point of view it is interesting to refer to the account of Chrysomyza Abietis, at 

 p. 155 of this Journal. 



