THE BEGINNINGS OF LIFE. 365 



Again, all that has been said with reference to these 

 general diseases is abundantly borne out by what we 

 know of local parasitic affections. Here, too, the 

 general or predisposing causes represented by the state 

 of the parts themselves, seem to be just as important 

 as the action of the special contagion indeed, in 

 multitudes of cases, the action of the special contagion 

 is assumed rather than proved to exist. Just as muscar- 

 dine can, apparently, be c spontaneously ' engendered in 

 almost any .caterpillars which are placed under certain 

 conditions, so does the Fungus-growth which is charac- 

 teristic of c thrush 7 manifest itself on the tongue and 

 adjacent parts of children under certain conditions, or 

 even on that of adults in the last stages of lingering 

 illnesses. The thoroughly healthy silk-worm is, more- 

 over, almost proof against contagion, just as the tho- 



a few days, is followed by signs of languor and great debility in the 

 animals operated upon, and is succeeded by a speedy death. Both 

 during life and after death, such animals possess myriads of Bacteria in 

 their blood. And yet the disease is not produced by the mere presence 

 of Bacteria in the local seat of irritation. I have several times injected 

 one or two drops of a fluid swarming with Bacteria beneath the skin of 

 frogs, without producing any such effects, or leading to the subsequent 

 presence of Bacteria in the blood. The cyclamen doubtless sets up 

 peculiar local changes, which are capable of spreading, so as to produce 

 a general disease in which the blood as well as other parts of the body 

 are affected ; and so far there is an agreement between such a process 

 and pyaemia in the human subject after wounds or operations. In the 

 latter case, however, the blood-changes are not such as to lead to the 

 evolution of Bacteria during the life of the individual ; whilst, in the case 

 of frogs inoculated with cyclamen-root, the changes in the blood do 

 lead to the evolution of organisms. 



