MAy 3, 1901.] 
(ONO,).CH,(ONO,), which when heated to 
257° C., or when struck, explodes with great 
violence. The products of the decomposi- 
tion are represented by the equation : 
4C,H,.(NO,)3 == 12CO, + 10H,0 + 6N, + 0). 
At the temperature of the explosion all 
these products are gases, and at atmos- 
pheric pressure will now occupy the space 
of about 10,400 liters, having expanded 
about 18,324 times its original volume. 
Another instance is that of mercury ful- 
minate [(C:N.O),.Hg + $H,0], which de- 
velops a pressure of 43,000 atmospheres 
by detonating in its own volume. 
Chemical changes partially or completely 
destroy the statically labile compounds, 
while the dynamically labile compounds 
readily pass into isomeric or polymeric 
compounds as a result of atomic migra- 
tions, or by polymerization. The classic 
illustration usually given of the produc- 
tion of an isomeric compound produced by 
atomic migration is Weehler’s famous dis- 
covery: the transformation of ammonium 
_ cyanate into urea, which he accomplished 
in 1828, by evaporating an aqueous solution 
of ammonium isocyanate. The transfor- 
mation is represented by the equation : 
= NH, 
O:C:N.NH,=~—0: C<NH, 
Many. others can be cited. 
Noting that labile compounds are more 
easily attacked by chemical agents than 
stable ones, Loew has elucidated the action 
of many poisons. He says: ‘‘ A systematic 
toxicological review shows us among other 
things that all compounds acting upon alde- 
hydes and all that easily attack labile 
amido-groups are poisonous for all kinds of 
living protoplasm, which fact led me to in- 
fer that the lability of the plasma proteids 
is caused by the presence of aldehyde and 
amido-groups within the same molecules. 
* * * The primum movens in the living 
protoplasm must be defined as a mode of 
motion of labile atoms in the plasma pro- 
SCIENCE. 
689 
teins ; that is, as a special case of chemical 
energy.’ According to Loew, the enzymes 
belong to the dynamically labile com- 
pounds. 
While the chemical structure of the en- 
zymes is not yet known the researches of 
Emil Fischer go to show that a knowledge 
of their constitution is not far beyond our 
reach. In the fermentation of the sugars 
Fischer has shown that the enzymes can 
only ‘attack those sugars which possess 
a molecular configuration corresponding 
to their own ’—that is, they must fit each 
other ‘as the key fits its lock.’ View- 
ing the enzymes as nucleo-proteid bodies, 
and as being optically active, he reasoned 
that their molecules must have an asymmetric 
structure. Their selective action toward a 
and @ methyl-glucosides strongly supports 
this view. 
According to Fischer, two methyl-glu- 
cosides are formed by the action of hydro- 
chloric acid (HCl) on a solution of d 
glucose in methyl alcohol, and their config- 
uration is given as follows : 
H.C .0.CH, CH,.0.C.H 
CH.OH ; Lom 
0) GHLOH (0) | ors 
Ae ie 
eran he arm 
ba.on buon 
One is called « the other 7, and their differ- 
ence is found in the configuration of the one 
asymmetric carbon atom, yet the enzymes 
which attack the « will not attack the £, 
and vice versa. This important discovery 
sheds a world of light upon the vexed prob- 
lem of fermentation, and will therefore help 
to explain many of the obscure phenomena 
of disease and of immunity. It will also 
find a place in the investigation of many of 
the difficult problems of physiological chem- 
istry. A very admirable feature of Fischer’s 
hypothesis is its capacity to receive aid 
