768 
and metabolism that the importance of 
the soluble ferments to the vital econ- 
omy is seen to the greatest advantage. 
According to Thompson,* ‘The power of 
growth, of adding to itself substance of the 
same nature as itself, is the real mystery of 
living matter.”’ So far as is known at 
present, it is mainly with growth that the 
enzymes areconcerned. Asa general thing 
they effect those changes which have to do ~ 
with nutrition, 7. ¢., with the digestion and 
assimilation of food on the part of the or- 
ganism. Asarule the enzymes bring about 
hydrolytic cleavages, the net result of which 
is to transform insoluble and non-absorb- 
able reserve or food materials into absorb- 
able and assimilable form. The transfor- 
mation of starch into sugar, the change of 
inulin into levulose and that of cellulose 
into glucose, the hydrolysis of fats and the 
conversion of albumen into peptone, are all 
important and interesting examples of en- 
zyme action. That the enzymes can also 
effect certain polymerizations and syntheses 
seems scarcely to admit any longer of a 
reasonable doubt; indeed, it seems not im- 
probable, in the light of our present knowl- 
edge, that many changes hitherto looked 
upon as resulting from the vital activity of 
the living cell itself may in reality be ac- 
complished through the instrumentality of 
aferment.+ Indeed it has been found that 
the soluble ferments stand in the closest pos- 
sible relation to the vital activities of the 
animal and the plant. For example, Ma- 
quene { has recently pointed out that the 
predominating, if not the only, role in the 
conservation and development of seeds 
must be attributed to the enzymes, and that 
*The Study of Animal Life,’ J. A. Thompson, 
p. 138. 
{See the work of Croft Hill ‘ Reversible Zymohy- 
drolysis.’—Jour. Chem. Soc., London (1898), Trans., 
634. Also, the work of Kastle and Loevenhart on the 
Synthesis of etheyl butyrate by lipase.—Am. Chem. 
Jour., XXIV., 491-525. 
{ Ann. Agron., 1900, 26, 321-332. 
SCIENCE. 
[N.S. Von. XIII. No. 333. 
the causes which retard the alteration and 
activity of the enzymes tend to maintain the 
germinating powers of seeds, and that, when 
preserved under conditions favorable to the 
enzymes remaining inactive, seeds may be 
kept indefinitely. 
In this connection Sachs* long ago 
pointed out that the so-called dormant 
periods of seeds and buds are probably in- 
tervals during which the necessary ferments 
are being produced in the cell. The vital 
relation of the enzyme to the living cell is 
also indicated by the fact that the ferment 
is often produced by the cell to meet some 
new necessity arising from a change in ex- 
ternal conditions or environment. For ex- 
ample, it has been found that the molds 
produce no diastatic or proteolytic enzymes 
so long as they are freely supplied with 
sugar. When cultivated on an albuminous 
medium, however, they speedily develop a 
proteolytic enzyme and on starch they soon 
produce diastase, and in the same connec- 
tion Bernard has observed that the larva 
of one of the common flies, Musca lucilia, 
contains a large amount of glycogen, but 
no diastase. As soon as the larva passes 
into the chrysalis stage, however, where the 
glycogen is required, a diastatic ferment at 
once makes its appearance. 
Apart from the production of several of 
the enzymes from their corresponding 
zymogens by the action of dilute acids, no 
enzyme has ever been produced outside of 
the living cell. In this connection it will 
be recalled that the zymogens are the 
mother substances of the ferments and 
that they in turn have never been produced 
outside of the living cell. In the light of 
these facts, the mode of origin of the fer- 
ments becomes a matter of considerable in- 
terest and importance. It has been proved 
that just as the nucleus and cytoplasm both 
participate in the formation of new cells by 
cell-division, so also both participate in the 
* Sach’s ‘ Plant Physiology,’ 1887, p. 352. 
