254 Proceedings of the Royal Society of Edinburgh. [Sess. 
it has to be kept in mind that the negative results of sub-cultures does not 
in itself constitute a positive proof of the sterility of the material from 
which they are made. Another point of some importance arises from the 
fact that absolute sterility is not necessarily required, but only absence of 
development, a fact worthy of consideration since it is obviously undesirable 
in cases such as those in question to employ any stronger antiseptic agent 
than absolutely necessary. 
The main part of the literature dealing with antiseptics from the point 
of view of efficiency is found in the publications of Salkowski and his co- 
workers, while more or less isolated statements occur throughout a large 
number of publications on both plant and animal physiology. The con- 
clusions thus arrived at, far from representing anything like a complete 
survey of the question, rather emphasise the necessity for more detailed 
and exhaustive inquiry, especially since many previously accepted anti- 
septics have been shown to be far from reliable, and since, even in the 
best cases, the efficiency seemed to vary with a large number of other 
factors. 
The literature on this point is naturally confined to the examination of 
a small number of antiseptics, since the large majority of germicides are 
out of the question for biochemical work owing to their too active nature, 
either chemically or otherwise. For this reason, the employment of 
inorganic acids and bases, as well as salts, is undesirable, since it is scarcely 
to be expected that an ionisable substance may be introduced into the 
condition under which these biochemical reactions take place without 
causing considerable disturbance in the said conditions. The same applies 
to a number of organic substances, while, even in the case of some of the 
less active compounds such as alcohol, their presence tends to disturb the 
colloid conditions and may even cause coagulation. 
Formaldehyde, hydrocyanic acid, benzoic and salicylic acids are, to 
some extent, also open to objection in this way; but, as these have been 
fairly extensively used for the purpose, it seemed desirable to subject 
them to examination, in order, at least, to determine the limits of their 
applicability. 
The main bulk of the literature concerns itself, then, with the following 
antiseptics : chloroform, formaldehyde, hydrocyanic, benzoic, and salicylic 
acids, thymol, toluol, and mustard oil. More or less isolated references 
are frequently met with in physiological and medical literature as to the 
employment of some antiseptic without any further remark as to the 
efficiency, the probability being that this was taken for granted and not 
demanding investigation. 
