

VEGETABLE PARASITES. 



GENERAL PART. 



"ALL vegetable parasites which are found on animal bodies 

 belong to the class Cryptogamia, and to the orders Alga and 

 Fungi exclusively." 



The medical man attends more particularly to those forms 

 which are met with in man/ and all the parasites treated of in tho 

 present work belong to the most simple plants, sometimes merely 

 formed by the aggregation of a number of cells, and they can, 

 therefore, scarcely be of a very complicated nature. Amongst 

 them the Alga are distinguished from the Fungi by chloro- 

 phyll, or some other colouring substance, which is observed at 

 their generation or soon after, and before the time when they 

 leave the parent-cell. If each cell is considered separately, the 

 smallest appear to be colourless, but are seen to be distinctly 

 coloured when they are aggregated into a mass. 



The investigation of the medium on which these parasites 

 are found is of importance for therapeutical purposes, and we 

 propose to view 



1. The solid ground or soil which affords them nourishment. 



2. The gaseous medium which surrounds them. 



3. The influence of physical agents upon them. 



1 . No plant can thrive on a merely mineral soil, but requires, 

 at the same time, organic substances ; if, therefore, parasitical 

 plants are to thrive, the animal system on which they live must 

 needs suffer from disturbance or want of nourishment, and a 

 simultaneous retardation of the change of elements. In conse- 

 quence of these changes, the renovation of the atomic elements 

 of the tissues and of the fluids proceeds so slowly, that the spores 



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