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physical power which leads to the formation of these artificial 
bodies, when long continued, causes their disintegration and destruc- 
tion. All these changes occur slowly, and require time ; but their 
contemplation, when regarded as purely physical phenomena, must 
strike us with surprise, as being closeiy allied to all our conceptions 
of the progress of life itself. 
Here the author explained, that in making use of the expressions 
life and vital action , he was only using terms to indicate phenomena 
which, in the present state of science, cannot be accounted for by 
the ordinary laws of physics. Or it might be said that certain 
actions are directed and governed by conditions which are as yet 
undetermined, but which, as they only occur in organic, as distin- 
guished from inorganic bodies, constitute vital actions. Not that an 
organised body is independent of physical forces, but that certain di- 
rections are communicated to them ; which, as invariably resulting in 
specific forms or properties, make up the sum of what we call vitality. 
Hence, although we see molecules combining in the forms of crystals 
and nucleated spherules, inasmuch as we have discovered the physical 
conditions on which they depend, and can produce them artificially, 
we have no difficulty in classifying these among purely physical 
phenomena, even when they occur in the interior of animals. But 
when other molecules unite to form nuclei, cells, and fibres, and 
these arrange themselves into tissues and organs to produce plants 
and animals, we are ignorant of the conditions by which these results 
are brought about — we cannot imitate them artificially, and are 
content to call them vital. But the fact the author was anxious 
to point out was this, that so far as observation and research had 
enabled us to investigate this difficult matter, it would appear that 
the formations and disintegrations of vegetables and animals, as 
well as the peculiar properties they exhibit, are essentially connected 
with the molecular element. Thus, when we investigate the functions 
of plants and animals — for example, generation, nutrition, secretion, 
motion, and sensation, — we find them all necessarily dependent on 
the permanent existence and constant formation of molecules. 
Thus generation, both in plants and animals, is accomplished by 
the union of certain molecular particles called the male and female 
elements of reproduction. Among the Protophyta, the conjuga- 
tion of two cells enables their contents, or the endochrome, to mix 
together. This endochrome is a mass of coloured molecules, and the 
