46 WHITMAN. [Vot. Il. 
organic, physiological, and biological units, are thus of the same 
general nature as those which compel us to discriminate be- 
tween physical and chemical units. Of course these higher 
units combine both atomic and molecular structure; but they 
have superadded to, and including this, a structure as a whole, 
which is entirely ignored in the expression “ molecular aggre- 
gates.” As they result from the union, not of simple or com- 
plex molecules, but of complex molecular groups, their structure 
may be said to be at least as widely separated from the mole- 
cule as this is from the atom. The power which such a unit 
represents as a whole is not the same as the powers represented 
by its constituent elements when uncombined, nor is it the sum 
of these several powers. Derived from them, and yet wholly 
unlike them, as water is something totally unlike its chemical 
elements or any simple mechanical addition of these elements. 
It is precisely this point which is so persistently ignored in 
all so-called physico-chemical theories of heredity. And yet 
all analysis and all observation leads to the conclusion, that 
molecular structure is not directly responsible for vital phe- 
nomena. In claiming that ‘physiological units” have some- 
thing higher than molecular structure and power, I am not 
treading on ultra-scientific ground, but following the course 
already sanctioned by chemistry and physics, and the only 
one which can ever reconcile physico-chemical and _ biological 
conceptions. 
Admit — what no one denies —that a molecule is totally 
unlike its constituent elements, that its energy is unlike that of 
its atoms, taken individually or collectively ; and further, that 
simple molecules, without losing their structural integrity, may 
unite to form complex molecules, and we have only to carry the 
same process a few steps farther to reach those units whose in- 
tegral structure is no longer adequately described as molecular. 
If analysis fails to discover a physiological bond which is capable 
of binding molecular aggregates into units of the vital order, 
its failure must be attributed to imperfection of methods, for 
observation bears constant and unvarying testimony to its ex- 
istence. If analysis and observation combine to show that 
whatever force an organism expends is the correlate and equiva- 
‘lent of force taken into it, and if chemical and physical pro- 
cesses underlie all vital phenomena, it does not by any means 
