vii.] OX THE PHYSICAL BASIS OF LIFE. 129 



condition, the /Etlialhim is an actively locomotive crea- 

 ture, and takes in solid matters, upon which, apparently, 

 it feeds, thus exhibiting the most characteristic feature 

 of animality. Is this a plant ; or is it an animal ? Is 

 it both ; or is it neither 1 Some decide in favour of the 

 last supposition, and establish an intermediate kingdom, 

 a sort of biological No Man's Land for all these ques- 

 tionable 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 

 animal, on the other, it appears to me that this pro- 

 ceeding 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 character. The researches of the chemist have 

 revealed a no less striking uniformity of material com- 

 position in living matter. 



In perfect strictness, it is true that chemical inves- 

 tigation can tell us little or nothing, directly, of the 

 composition 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 somewhat frivolous, have been raised to the 

 drawing of any conclusions whatever respecting the 

 composition of actually 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 anyjoody whatever, as it is. The state- 



