vii.] ON THE PHYSICAL BASIS OF LIFE. Ill 



by a particle of protoplasm without a nucleus. Nor are such 

 organisms insignificant by reason of their want of complexity. 

 It is a fair question whether the protoplasm of those simplest 

 forms of life, which people an immense extent of the bottom of 

 the sea, would not outweigh that of all the higher living beings 

 which inhabit the land put together. And in ancient times, no 

 less than at the present day, such living beings as these have 

 been the greatest of rock builders. 



What has been said of the animal world is no less true of 

 plants. Imbedded in the protoplasm at the broad, or attached, 

 end of the nettle hair, there lies a spheroidal nucleus. Careful 

 examination further proves that the whole substance of the nettle 

 is made up of a repetition of such masses of nucleated proto 

 plasm, each contained in a wooden case, which is modified in 

 form, sometimes into a woody fibre, sometimes into a duct or 

 spiral vessel, sometimes into a pollen grain, or an ovule. Traced 

 back to its earliest state, the nettle arises as the man does, in a 

 particle of nucleated protoplasm. And in the lowest plants, as: 

 in the lowest animals, a single mass of such protoplasm may 

 constitute 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 &quot; plant &quot; and the other &quot; animal &quot; ? 



The only reply is that, so far as form is 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 jEthalium 

 septicum, which appears upon decaying vegetable substances, 

 and, in one of its forms, is common upon the surfaces of tan-pits, 

 In this condition it is, to all intents and purposes, a fungus, and 

 formerly was always regarded as such ; but the remarkable in 

 vestigations of De Bary have shown that, in another condition, 

 the JEtkalium is an actively locomotive creature, and takes in 

 solid matters, upon which, apparently, it feeds, thus exhibiting 

 the most characteristic feature of animality. Is this a plant ; or 



