82 NO VEGETABLE ORGANISMS 



and that yet other fungi, also unknown at this time, 

 exist, which are only able to produce their effects in 

 organisms changed by certain previous actions for 

 their reception, and this, in spite of the fact that no 

 connection whatever has been shown to obtain between 

 any contagious disease and any kind of fungus. 



But yet in favour of such a doctrine it might be 

 urged with truth, that some parasitic organisms affect 

 all indiscriminately, while others require certain preli- 

 minary changes to be carried out before the various 

 parts of the organism they delight in are adapted for 

 their habitation and are rendered favourable to their 

 increase. It must not, however, be forgotten that 

 parasites which are known exhibit at one or other 

 stage of existence certain well-marked characters by 

 which they may be recognised with the utmost cer- 

 tainty, and this is especially the case with parasitic 

 vegetable organisms, many of which can be grown 

 artificially without much difficulty, and studied in the 

 several different stages of their development. 



Those who look with partiality upon the vegetable 

 germ theory of disease should consider how the absence 

 of any bodies like vegetable fungi in animal fluids and 

 solids, proved by experiment to possess active infectious 

 properties, is to be accounted for. Not only is it the 

 case that vegetable organisms are not to be found 

 in the perfectly fresh virus when it is most active, but 

 no specific form of vegetable growth can be developed 

 from the particles which do exist, as would almost 



