766 
Persoz in 1833, or to Bussy, when in 1840 
he wrote that up to that time it had not 
been possible for him to obtain myrosin 
in crystalline condition. Apart from this 
uncertainty respecting their chemical com- 
position, however, there has been a grow- 
ing conviction in the minds of many most 
familiar with the peculiar and remarkable 
properties of these substances, that in the 
soluble ferments we have to deal with cer- 
tain subtle and peculiar activities similar 
to those manifested by the living organism 
itself. The idea that the enzymes retain at 
least some vestiges of the original activity 
of the cell or organ of which they once 
formed a part is one that has appeared 
again and again in the scientific litera- 
ture of the last twenty years with a curi- 
ous persistency and under almost as 
many different guises as the proteid mole- 
cule itself is supposed toassume. According 
to Loew,* who was probably the first to ad- 
vance any ideas of this kind, the enzymes 
are to be regarded as active or labile proteids 
or peptones, the activity of which is probably 
traceable to the presence of amido and al- 
dehyde groups in the molecule, and whose 
instability isin some way connected with 
various molecular rearrangements involvy- 
ing these groups. He has also pointed out 
that many of the so-called. protoplasmic 
poisons are just such substances as are 
known toreadily attack amido and alde- 
hyde groups in organic molecules, and 
it was in this connection that Loew first 
called attention to the silver reduction test 
as a means of distinguishing between ac- 
tive and inactive ferments and dead and 
living protoplasm. According to Loewy 
the conversion of the albumin of living 
into that of dead protoplasm presents a re- 
markable analogy to the transformation of 
an unstable substance into its stable modi- 
* Pfliiger’s Archiv., 27 (1882), 203, and'36 (1885), 
170. 
{Pfltig. A., 65, 249, 1897. 
SCIENCE. 
(N.S. Vou. XIII. No. 333. 
fication. Such a transformation, for ex- 
ample, as is met with in the change of the 
yellow iodide of mercury into the more per- 
manent red variety of this compound. 
In the same way Medwedew,* like Loew, 
has found it necessary to assume that cer- 
tain of the enzymes at least possess a re- 
siduum, as it were, of the vital forces of 
the living cell; and finally Armand (sautier 7 
has gone even further in his assumptions 
and has taken the extreme view that the 
enzymes are to be regarded as dissolved cells, 
and that in addition to their other remark- 
able properties, they possess in common 
with other cells the power of assimilation 
and reproduction. Remarkable and sug- 
gestive as these ideas certainly are, they do 
not seem to have met with anything like 
general acceptance at the hands of biolo- 
gists; indeed, in certain quarters, at least, 
they have encountered a very vigorous and 
decided opposition, and by some have been 
pronounced as far too vague to constitute 
even a satisfactory working hypothesis.t 
Apart from the fairness and justice of this 
criticism, there can be no doubt that, 
in his earlier work upon this subject, at 
least, Loew was inclined to lay too much 
stress on the silver reduction test as the 
basis of a sharp and accurate distinction 
between active (living) and iactive (dead) 
proteid; and while the terms splinters of 
protoplasm and dissolved cells may appeal very 
strongly to the poetical side of our nature, 
it cannot be denied that they are far too 
hazy to express with any sharpness of 
definition a scientific truth. 
On the other hand, it would seem to the 
layman, particularly if he happen to be a 
chemist, that the whole trend of modern 
biology, until very recently at least, has 
been toward form rather than substance, 
and that all of the efforts of the biologist to 
* Pfliig. A. 65, 249, 1897. 
+See Effront, ‘Les Diastases.’ 
+See Pfeffer’s ‘ Plant Physiology,’ 67, 69, 1900. 
