34 
Proceedings of Royal Society of Edinhurgh. [dec. 5 , 
tinguislied Society further details relative to these investigations. 
The principle of these researches is to find some germicidal agent 
capable of destroying the microbes of disease, which have been 
proved to reside in the blood, and are the causes (directly or in- 
directly) of certain contagious diseases. At the same time, an 
aqueous solution of such an agent, while destroying the microbes of 
disease, must have very little or no detrimental action upon the 
blood. Having found such a substance, the rationale is to inject 
(hypodermically) a solution of the microbe-destroyer directly into 
the blood. By so doing, the destruction of the pathogenic organ- 
isms in situ would be the result. 
In my last memoir on this subject (Jioc. cit.) aqueous solutions of 
salicylic acid were shown to materially interfere with the life-his- 
tories of certain micro-organisms. In the present paper an account 
will be given of the action of various antiseptic and germicidal 
agents upon certain microbes and their spores, as well as a practical 
application of my method in a particular case of advanced phthisis. 
I. Alkaloids produced by Living Microbes. 
It appears, as pathological investigations progress, the real cause 
in many cases of contagious diseases (although not in all) is the for- 
mation of certain poisonous compounds (ptomaines or alkaloids) 
by living microbes ; rather than the idea that the mere presence 
of these microbes in the blood or tissues causes such diseases. 
It will be remembered that in 1885 Pouchet discovered the 
ptomain formed by the Comma Tjacillus ; and being very soluble, is 
easily absorbed into the system. Hence the rapidity of death fol- 
lowing the first symptoms of the disease. 
Amongst very recent work on the subject of ptomaines, produced 
by pathogenic and other microbes, we have the following ; — (a) Dr 
O. Bocklisch {Berichte der deutschen chemischen Gesellscliaft, vol. 
XX. p. 1441) found that Vibrio proteus produced in contact with 
sterilised beef cadaverine (CgH^^Hg) which had been proved by 
Ladenburg {Berichte der deutschen chemischen Gesellschafty vol. xix. 
p. 2585) to have all the chemical properties of pentam ethylene- 
diamine (C 5 HJ 4 H 2 ). This alkaloid or ptomaine of Vibrio proteus 
(Tinkler’s bacillus) is non-poisonous. Bocklisch went a step further, 
and found that when Vibrio proteus was allowed to live upon 
