184 J. LAGNET TAY LER [SEPTEMBER 
different results. These two forms have developed on their separate 
lines and have resulted in the most important divisions of organic 
life, the animal and vegetable kingdoms; and the most marked 
difference between these two kinds of protoplasm appears to lie in 
the fact that one has to exist on comparatively complex foods, the 
other on comparatively simple. Excluding this and other differences, 
for the moment, from consideration, there remain three peculiarities 
which distinguish protoplasm from inorganic material:—(1) It is 
extremely complex in structure; (2) it is remarkably unstable; and 
(3) it has the power, when placed under suitable conditions, of build- 
ing up from its environment material similar to or identical with its 
own. 
Lewes, Spencer, and, in a crude unscientific form, many early 
writers, have noticed certain resemblances between some kinds of dead 
and living material; these resemblances have steadily multiplied in 
number, while they have become far more forcible in character during 
the last forty to fifty years, so that many, perhaps most, scientists are 
beginning to assume, consciously or unconsciously, that purely physical 
and chemical causes are or soon will be sufficient to explain the lower 
and possibly also the higher forms of life.’ Let us take first the pecu- 
liarities of protoplasm which are apparently most alhed to chemical and 
physical phenomena, its extreme instability and complexity. Making 
a general statement of the characteristics of the chemical elements, it 
appears that they may be grouped into three more or less ill-defined 
divisions—those with marked affinities, others with very ill-marked 
tendencies, and a third intermediary division. Stability is usually 
associated in chemistry with simple molecular structure; satisfied 
affinities and compounds are generally stable when they are made up 
of elements which exhibit strong mutual affinities, combined in such a 
way that each tendency is more or less completely balanced by others. 
The more perfectly the elements are brought into contact, the more 
combination of these elements is accelerated, and, finally, there is an 
evolution of energy whenever the less stable passes into the more 
stable. 
Chemical instability, on the other hand, is associated with weak 
affinities, great complexity, and a combination of elements in a form 
which by readjustment might lead to the formation of simpler 
and more stable compounds. As there is always an evolution of 
energy when the less stable passes into the more stable, there is 
manifestly a storage of potential energy in the unstable forms. The 
instability and complexity of protoplasm is therefore really not a 
difference from, but a resemblance to, non-living substances, because 
its instability and complexity apparently exist under similar, though 
accentuated, conditions to those cases where the complexity and in- 
stability is purely chemical. The distinctive characteristic of living 
? 
' Verworn in his ‘‘ General Physiology” gives a fairly complete summary of this position. 
