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light, you will see a black cross produced in tbe granules— produced in the 
passage of this light through these granules. The Professor then goes on to say 
that just as the black cross results from the crystallization of the calcite, so 
the black cross results from the organic formation to which he alludes. But 
the two things are totally different, which he ought very well to know, and 
rest on totally different grounds. The effects manifested by the passage of 
polarized light through a crystal are invariably the same from whatever 
source the crystal is derived, and if you have a mass, and take the smal es 
portion of any part of that mass, you will find that exactly the same effects 
are produced by the transmission of polarized light. The molecules of whic 
it is composed are arranged in a certain definite order in the way m which 
Mr Howard has happily shown in the early part of his paper, whereas m 
starch-grains the case is totally different. The action of polarized light on 
starch-grains results entirely from their being in a state of strain, and any 
inorganic substance which is in a condition of strain will exhibit certain 
effects in a polarized ray. Now any organic substance, such as horn, or a 
great many other substances when perfectly dry, desiccated as starch 
granules are, and which in the process of desiccation have undergone a 
certain amount ol molecular strain, show under that condition of strain a 
peculiar action on polarized light. Just the same thing takes place with a 
piece of unannealed glass. Unannealed glass is very readily broken y 
the action of heat, or any mechanical disturbance of its molecules Take, tor 
instance, Rupert’s drops, small pieces of glass suddenly cooled by being 
dropped into water. The exterior is more rapidly cooled than the interior, 
and a contraction is produced which occasions a strain on the interior mole- 
cules. So if you take a piece of unannealed glass you will find, on sub- 
mitting it to the action of a polarized ray, that you will have a black cross 
But it is far from corresponding with the crystal, whereas if t e piece o 
class were a crystal of calcite, every part of it would present exactly the 
same character under the action of polarized light. But whereas m a piece 
of unannealed glass it results from a strain, if you cut off the sides of a , circ e 
and reduce them to a square you will have very different figures produced. 
So if you take a circle and scallop its circumference, you will then have a 
totally different figure produced, because in that case you have removed the 
external strain in rather a different manner. I think this is quite sufficient 
to explain to you that the analogy is a totally false one, and that it is no 
true that just as the black cross is in the one case so it is in the other, u 
that there are two somewhat similar results produced by totally different 
causes I have brought this forward as one of the specious arguments which 
some men of science will put forward, I might almost say, in order to mislead 
the unwary. I hope that some of our friends will make some observations upon 
Mr Howard’s paper. It appears to me to be most important that the clearest 
and most intelligible conception should be given to the unscientific, as to the 
fundamental distinction that exists between the results of any mere mole- 
cular action, and organization which is the result of vitality. And it must 
always be borne in mind that whereas in the case of inorganic formation the 
