CHAP, vi.] OF LIVING LIQUIDS. 53 



special molecular affinities, refusing, for instance, as long as it is 

 living, to let itself be imbibed by colouring matters. Now we 

 know that this intracellular protoplasma offers all the chemical 

 reactions of the true albuminoidal matters (albumine, fibrine, 

 easeine). Iodine gives it a yellow colour ; alcohol, the mineral 

 acids, and heat coagulates it. 



Chemically, the vegetal blastemas are constituted by water, 

 by albuminoidal substances, and by some salts. 



2. Animal Blastemas. 



There has been a wish to limit the name of blastemas, in the 

 animal economy, to the interstitial liquids alone in which new 

 anatomical elements are formed, that is to say, to the intercellu- 

 lar liquids of the animal embryons, before the formation of the 

 vessels, to the organisable liquids which are produced in a wound 

 in process of cicatrisation, finally to the liquids of the serous 

 cavities. But in biology, as in all other natural sciences, if it is 

 useful to divide, to classify, it is wise not to accord to divisions 

 and classifications an absolute value. The frontiers which we are 

 obliged here and there to mark out in the vast field of the living 

 world to aid the feebleness of our memory have only a relative 

 value. In effect, in the organic world, even taken generally, all 

 is gradual modification, gradual transition. If this is true, as 

 incontestably it is, in the classifications of natural history, 

 properly so-called, how much more must it be so when the aim is 

 to ascertain the constituent parts of one and the same organism 1 

 If we reserve the name of blastemas to the small number of 

 liquids living, interstitial, organisable, and generative, what are 

 we to do with the other interstitial liquids, with those which 

 bathe the elements of the tissue called conjunctive [connective], 

 of that tissue comparatively coarse in its morphology which 

 serves as gangue and as support to all the others ? And in most 

 tissues, wherever the elements do not touch each other at every 

 point of their surface, is there not an interstitial liquid, coming 



