11 



the lowest animals, a single mass of such protoplasm may consti- 

 tute the whole plant, or the protoplasm may exist without a 

 nucleus. Under these circumstances it may well be asked, how 

 is one mass of non-nucleated protoplasm to be distinguished from 

 another? why call one " plant," and the other "animal ?" The 

 only reply is that, so far as formSs concerned, plants and animals 

 are not separable, and that, in many cases, it is a mere matter of 

 convention whether we call a given organism an animal or a plant. 



There is a living body called uTJthaliwm sejyticum^ which 

 appears upon decaying vegetable substances,and in one of its forms, 

 is common upon the surface of tan pits. In this condition it iF> 

 to all intents and purposes, a fungus, and formerly was always 

 regarded as such ; but the remarkable investigations of De Bary 

 have shown that, in another condition, the ^thallum is an ac- 

 tively locomotive creature, and takes in solid matters, upon 

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

 tic feature of auimality. Is this a plant, or is it an animal? Is 

 it both, or is it neither? Some decide in favor of the last suppo- 

 sition, and establish an intermediate kingdom, a sort of biologi- 

 cal 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 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. .^ -^ ^ ^^^^^^^ c^^^^^^^^^^.. ; 



The researches of the chemist have revealed a no less strik- 

 ing uniformity of material composition in living matter. In per- 

 fect strictness, it is true that chemical investigation can tell us lit- 

 tle or nothing, directly, of the composition of living matter, inas- 

 much 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 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 



