ON THE PHYSICAL BASIS OF LIFE 99 



shown that, in another condition, the jEthalium is an ac- 

 tively locomotive creature, and takes in solid matters, upon 

 which, apparently, it feeds, thus exhibiting the most char- 

 acteristic feature of animality. Is this a plant; or is it an 

 animal ? Is it both; or is it neither? Some decide in favour 

 of the last supposition, and establish an intermediate king- 

 dom, a sort of biological No Man's Land for all these 

 questionable forms. But, as it is admittedly impossible 

 to draw any distinct boundary line between this no man's 

 land and" the vegetable world on the one hand, or the ani- 

 mal, on the other, it appears to me that this proceeding 

 merely doubles the difficulty which, before, was single. 



Protoplasm, simple or nucleated, is the formal basis of 

 all life. It is the clay of the potter: which, bake it and paint 

 it as he will, remains clay, separated by artifice, and not 

 by nature, from the commonest brick or sun-dried clod. 



Thus it becomes clear that all living powers are cognate, 

 and that all living forms are fundamentally of one charac- 

 ter. The researches of the chemist have revealed a no less 

 striking uniformity of material composition in living matter. 



In perfect strictness, it is true that chemical investiga- 

 tion can tell us little or nothing, directly, of the composi- 

 tion of living matter, inasmuch as such matter must needs 

 die in the act of analysis, — and upon this very obvious 

 ground, objections, which I confess seem to me to be some- 

 what frivolous, have been raised to the drawing of any 

 conclusions whatever respecting the composition of actu- 

 ally living matter, from that of the dead matter of life, 

 which alone is accessible to us. But objectors of this class 

 do not seem to reflect that it is also, in strictness, true that 

 we know nothing about the composition of any body what- 

 ever, as it is. The statement that a crystal of calc-spar 

 consists of carbonate of lime, is quite true, if we only mean 



