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 take a given crystalline form. It is from experiments such as this that we derive the idea of ''a specific form connected with a chemical constitution''.

But in drawing this conclusion our logic is at fault. The real interpretation suitable to this case, as in all others, is that the specific form is suitable to the substance, and also to the physical, chemical, and mechanical conditions in which it is placed. And the proof is that this same substance, sulphur, which takes the prismatic form immediately after fusion, will not retain that form, but will pass on to the quite different octahedral form.

It is so with the specific form of the living being—that is to say, with the assemblage of its constituent materials co-ordinated in a given system—in a word, with its organization. This is suitable to its substance, and to all the material, physical, chemical, and mechanical conditions in which it is placed. This form is the condition of material equilibrium corresponding to a very complex situation, to a sum of given conditions. The chemical condition is only one of these. And further, it is hardly proper to speak of a "chemical substance" when we refer to an astonishingly complex mixture which is in addition variable from one point to the other of the living body. When we thus reduce phenomena to their original signification, false analogies disappear. To say with Le Dantec that the form of the greyhound is the condition of equilibrium of the "greyhound chemical substance" is saying much; and too much, if it means that the body of the greyhound has a substance which behaves in the same way as homogeneous, isotropic masses like melted sulphur and dissolved salt. It were better to say much less, if it