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Proceedings of the Royal Society 
destroyed, that its life has departed, and that the chemical solution 
is a true germicide j while if, on the contrary, although while in 
the solution the spore did not grow, yet, on being placed on 
suitable soil, there is either feeble or strong growth, in that case, 
although the solution may have disinfectant properties, it is not a 
germicide. 
Much more has been done to show the disinfectant than 
the germicidal properties of substances. The labours of Angus 
Smith, Grace Calvert, Bucholz, and other workers have studied 
the inhibition of fungoid growth and of putrefaction, the 
destruction of odours, and the decomposition and fixing of noxious 
gases; so that further observations on the same lines would 
scarcely do more than confirm facts generally accepted. 
But the action of chemical agencies on those minute particulate 
substances which are regarded as the materies morhij or seeds of 
zymotic and parasitic diseases, have been but little investigated. 
Here is a field for investigation of almost illimitable extent, but 
nevertheless one in which we have already firm paths and footholds 
across the morass of theory and conjecture, as, for example, in 
Gerlach and Franck’s experiments on the virus of glanders, Ledra 
on that of ovine variola, and Braidwood and Vacher on the lymph 
of vaccine. 
Of all moderns who have directed their attention to disinfectants. 
Dr Koch stands chief ; and his masterful monograph, “ Ueber 
Desinfection ” (published in Mittlieilungen aiis dem Kaiserlichen 
Gesundheitsamte herausgegehen^ von Dr Struck, Berlin, 1881), will 
long remain an example and guide to future explorers. 
In my own experiments I have followed out in principle, 
although not in detail, Koch’s method. 
Koch’s observations were on the Anthrax hacillas^ and at the 
commencement of my experiments no organism seemed so perfectly 
adapted for the trial of the germicide power of disinfectants, for — 
(1) The morphology and life history of the Anthrax bacillus has 
been worked out with some completeness. 
(2) When necessary, its vitality may be tested by inoculation. 
(3) It exists in two states — the thread form, readily attacked by 
chemical and physical agencies, and the spore form, destroyed with 
great difficulty. 
