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The Chairman. — I am sure we must all with acclamation return our 
thanks to Mr. Howard for his very able and excellent paper. In commencing 
the discussion, it may perhaps be agreeable to you that I should point out 
one or two of the palpable fallacies which have been put forward in support 
of the doctrine so admirably controverted in this paper — namely, that there 
is a strict analogy between the inorganic processes, such as the formation of 
a crystal, and the organic processes, such as the formation of a living being. 
On one occasion, at a meeting of the British Association, I remember a 
lecture was addressed to the working men of Dundee, and I could not help 
thinking what a pity it was that so false an analogy should be specially 
addressed to the working men of one of the great centres of Scotch industry, 
who were so little capable of recognizing the very limited extent of the 
analogy placed before them. Professor Tyndall, who gave the lecture, called 
attention to the resemblance to the formation of what we may call fern-like 
leaves, by what is commonly known as the production of the zinc-tree or the 
lead-tree. If you place a solution of sugar of lead in a bottle and hang a 
little ball of zinc at the top of the bottle, and wait a certain time, beautiful 
leaf-like formations will take place, which in fact result from the acetic acid 
of the sugar of lead taking up the zinc and setting free the lead. The lead 
forms thin laminated crystals, which are thrown out, and are very fern-like 
in appearance. The argument of the lecturer was that just as this action 
produces fem-like branches, so the real ferns are produced by analogous 
means. But there is a fundamental error underlying this proposition. It is 
simply this : that under whatever circumstances and from whatever source 
you derive it, exactly the same form takes place in the crystallization of lead, 
or the crystallization of silver, or of any other substance. If you re-dissolve 
it exactly the same thing may again take place, whereas in the formation of 
plants we know that the same elements of carbon, hydrogen, oxygen, and 
more or less of nitrogen, with portions of lime and silica, meet as air, water, 
and earth, and form these plants, but do they always form the same ? No, 
certainly not. The individual plant formed depends on the influence of the 
pre-existing germ derived from another organism of the same kind, which 
determines the particular mode of combination of the inorganic element, so 
as to form an individual similar to that from which the germ was derived : 
there is the essential difference. You have the same elements producing 
every variety of plant from the soil and the air according to the influence of 
the seed — that is, of a germ derived from a similar organism, whereas in the 
simple inorganic formation of a crystal you have exactly the same crystal 
formed from whatever source you derive the crystallizing element. Another 
error of the same kind, and what was more subtle, was put forward in a work 
by Professor Tyndall, called “ Fragments of Science for Unscientific People,” 
in which he refers to polarized light. It is well known that. if you take a 
section of crystallized carbonate of lime in a direction perpendicular to the 
axis of the crystal, and expose it to the action of a polarized ray, you have a 
series of rings with a black cross. If you take certain organic elements, such 
as particles of arrow-root or starch-grains, and examine them under polarized 
