666 TRANSACTIONS OF SECTION I. 
content to quote a single instance out of many. Twort has shown that certain 
bacteria of the Coli-typhosus group can be trained to split sugars and alcohols 
which originally they could not split at all. A strain of B. typhosus which after 
being grown upon a medium containing dulcite had acquired the power of 
splitting this substance, retained it permanently, even after passage through 
the body of the guinea-pig, and cultivation upon a dulcite-free medium. Similar 
observations have been made upon the Continent by Massini and Burri; the 
latter showed by ingenious experiments that all the individuals of a race which 
acquires such a new property have the same potency for acquiring it. No one, 
at the present time, will deny that the appearance of a new enzyme is involved 
in this adjustment of the ceil to a new nutritive medium. 
We have not, it is true, so much evidence for similar phenomena in the case 
of the higher animals. The milk-sugar splitting ferment may be absent from 
the gut epithelium before birth, and in some animals may disappear again after 
the period of suckling, but here we probably have to do with some simple 
alternation of latency and activisation. But among the ‘ protective’ ferments 
studied by Abderholden we have, perhaps, cases in which specific individuals 
appear de novo as the result of injecting foreign proteins, &c., into the circula- 
tien. Consider, moreover, the case of the reactions called out by simpler 
substances. We have seen that an enzyme separable from the kidney tissue 
can catalyse the synthesis no less than the breakdown of hippuric acid. Now 
the cells of the mammalian kidney have always had to deal with benzoic acid 
or chemical precursors of benzoic acid, and the presence of a specific enzyme 
related to it is not surprising. But living cells are not likely to have ever been 
in contact with, say, bromo-benzol, until the substance was administered to 
animals experimentally. Yet a definite reaction at once proceeds when that 
substance is introduced into the body. It is linked up, as we have seen, with 
cystein. Now, this reaction is not one which would proceed in the body un- 
catalysed; if it be catalysed by an enzyme, all that we know about the 
specificity of such agents would suggest that a new one must appear for the 
purpose. I have allowed myself to go beyond ascertained facts in dealing with 
this last point. But once we have granted that specific enzymes are real agents 
in the cell, controlling a great number of reactions, I can see no logical reason 
for supposing that a different class of mechanism can be concerned with any 
particular reaction. 
If we are entitled to conceive of so large a part of the chemical dynamics 
of the cell as comprising simple metaplasmic reactions catalysed by independent 
specific enzymes, it is certain that our pure chemical studies of the happenings 
in tissue extracts, expressed cell juices, and the like, gain enormously in 
meaning and significance. We make a real step forward when we escape 
from the vagueness which attaches to the ‘bioplasmic molecule’ con- 
sidered as the seat of all change. But I am not so foolish as to urge that the 
step is one towards obvious simplicity in our views concerning the cell. For 
what indeed are we to think of a chemical system in which so great an arrav 
of distinct catalysing agents is present or potentially present; a system, I 
would add, which when disturbed by the entry of a foreign substance regains 
its equilibrium through the agency of new-born catalysts adjusted to entirely 
new reactions? Here seems justification enough for the vitalistic view that 
events in the living cell are determined by final as well as by proximate causes, 
that its constitution has reference to the future as well as the past. But how 
can we conceive that any event called forth in any system by the entry of a 
simple molecule, an event related qualitatively to the structure of that mole- 
cule, can be of other than a chemical nature? The very complexity, therefore, 
which is apparent in the catalytic phenomena of the cell to my mind indicates 
that we must have here a case of what Henri Poincaré has called Ja simplicité 
cachée. Underlying the extreme complexity we may discover a simplicity 
which now escapes us. If so, I have of course no idea along what lines we 
are to reach the discovery ot that simplicity, but I am sure the subject should 
attract the contemplative chemist, and especially him who is interested and 
versed in the dynamical side of his subiect. If he can arrive at any hypothesis 
sufficiently general to direct research he will have opened a new chapter ot 
organic chemistry—almost will he have created a new chemistry. 
Tt must not be supposed that I am blind to the fact that the phenomena 
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