of Edinburgh, Session 1884 - 85 . 
271 
which, they act, hut set free a very large proportion of elaborated 
food material which may he applied to the use of the organisation 
in which the process is carrried on. It would appear that this same 
law governs the processes set up by micro-organisms in the tissues 
of their host in several of the specific infective diseases, and that 
the products of the fermentation set up, are applied, at least in part, 
to the nutritive purposes of the organisms themselves, and, in part, 
to prepare living or only partially devitalised tissues for further 
assimilative processes on the part of these micro-organisms. But 
beyond this, in some cases, a product is elaborated which, acting as an 
antiseptic, destroys the vitality of the organism which produced it. 
The existence of these special products is now generally 
acknowledged. They are not necessarily accompanied in tbeir 
distribution by the organism which produced them on account of 
their greater diffusibility. The organism will, however, usually he 
found at some point whence absorption of its products might occur. 
In those cases where it is not found in such a position, and where 
typical traces of its action may he met with, we have abundant 
evidence that, owing to the exhaustion of the material necessary for 
its nutrition, it has ceased to exist, but its progeny have migrated 
to, and are found in, the less altered tissues in the immediate 
neighbourhood, prepared for their reception by the products of the 
primary fermentative process. 
Up to this point the paper deals with the subject of the organised 
irritant agent ; we must next turn to the reactions brought about in 
the cell elements of the invaded tissues, and we shall find that these 
reactionary changes have a definite relation to the nature of the 
irritant and the conditions under which it is applied. Under 
normal and constant conditions we might anticipate that the cells 
of any part of one of the higher organisms would continue to be 
reproduced at a fixed rate, to perform their function and die, a 
regular proportion of young, functionally active and dying cells, 
being maintained throughout. We know, however, that such a 
cycle, if left alone goes on for a certain period only, and that there 
comes a time at which the reproduction is not equal to the removal, 
and that consequently organic death takes place, and the species 
dies out if the process is not again commenced ab ovo. But there 
are conditions in which the regular cycle is interfered with. The 
