^So^na^Sr^ Spontaneous Generation, 255 
displays. A further stage of evolution is readied when the very 
imperfectly integrated molecules forming one of these minute 
aggregates become more coherent, at the same time as they pass 
into a state of heterogeniety, gradually increasing in its definite- 
ness." 
Dr. Winslov?-,* in speaking of the forces exerted upon mole- 
cular matter, says, " In whichever light we study the action and 
reaction of these binary elements of mechanical energy, or vis, we 
observe all the phenomenal results in crystals, plants, or animals 
to develop themselves upon crucial and bilateral principles, and all 
the secondary forces to follow the same axial and equatorial lines of 
propagated molecular force and motion." 
This is exemplified in a remarkable manner in the molecular 
movements in all the experiments that I have instituted. We first 
observe a homogeneous molecular mass (Plate XXXII., Fig. 1) float- 
ing or suspended in water, which has been added ; and almost as soon 
as the infusions have become cold we observe a remarkable movement 
has taken place with the molecules ; part of this is, I presume, from 
the loss of heat. They have already begun to form themselves into 
some definite shape (Fig. 2). There have, then, been forces at work 
imperceptible to us, except that we see the results of those powers 
in the formative process that is going on. The same, or apparently 
the same, formative process may be seen, I admit, in the act of 
crystallization, as the suspended molecules are drawn towards each 
other by a force that is termed afiinity or attraction ; but when the 
crystal is formed, the process is complete. This same process may 
be repeated by the addition of other and similar crystals, but this 
is all ; here crystallization ceases ; it can go no farther. The same 
laws that govern both organic and inorganic matter, when each are 
placed in similar conditions, appear to act the same on both ; the 
same influences are exerted on both, and apparently in the same 
degree ; indeed, the two seem to run in parallel lines to a certain 
distance ; at last the inorganic stops ; it has reached its ultimate 
form. Its hitherto companion is still acted on by the same forces : 
it is carried forward, and here the true vis vitae, or life-force, is 
really seen. We now see distinctly the difference between the 
organic and the inorganic kingdoms. When the two started, we 
saw what we believed to be the same energy acting equally alike 
on both — the vis or force, the vitse or principle of life, had not then 
manifested itself. 
But the very fact of life being transmitted or carried forward 
implies a force or energy. At the same time "it is not a mere 
mechanical force, such as we saw at work in the formative process 
of crystallization, but a life-force, a force that implies that some 
other and peculiar property is bound up with these mechanical forces. 
* ' Force and Nature,' p. 282. 
