394 LABILITY AND ENERGY IN RELATION TO PROTOPLASM. 
“ Let us turn to consider a difficulty in connection with Dr. 
Loew’s hypothesis—a difficulty involved in the whole conception 
of lability. The difficulty will be best explained by a concrete 
example. “ One of the most interesting labile atomic groups,” 
says Dr. LOEW, “ is the aldehyde group, —in which the 
oxygen exerts an attracting influence upon the hydrogen con¬ 
nected with the carbon atom, this being generally tetravalent, 
but sometimes only bivalent. The hydrogen atom is thus ever 
oscillating between the carbon and the oxygen, as may be in¬ 
dicated by the following formulae :— 
-C<^ -C-O-H -C<^ -C-O-H 
(i) ( 2 ) (3) (4) 
“ The hydrogen atom may be conceived as oscillating between 
the carbon atom and the oxygen atom, as the contact-breaker of 
a faradic battery oscillates between the electro-magnet and the 
connecting point to the longer circuit. The defect in the analogy 
we have chosen serves to point the difficulty of which we have 
spoken. The oscillation of the contact-breaker depends on two 
forces that alternately become effective in opposite directions, the 
force of the electro-magnet overpowering the force of the spring, 
and the force of the spring when the electro-magnet has ceased 
to act. But can we find any similar play of alternating forces in 
our hypothetically constructed labile compound ? It does not 
seem so. It is certain that the attractive force between two 
chemical atoms increases enormously as the distance between 
the atoms diminishes. Let us suppose our hydrogen atom to be 
placed initially between the oxygen atom and the carbon atom in 
such a manner that the pull is equal in both directions. If the 
hydrogen atom now moves in the direction of, say, the carbon 
atom, the attraction of the carbon atom at once becomes much 
greater than that of the oxygen atom, and the —form should 
be permanently assumed. 
“ Does, then, Dr. Loew conceive that in a labile group 
something takes place analogous to the changes in the faradic 
battery when the contact-breaker is vibrating ? that the move¬ 
ment—to return to our example—of the hydrogen atom towards 
the carbon atom brings about a state of molecular forces within 
