128 LAY SERMONS, ADDRESSES, AND REVIEWS. |vn 



wlictlicr 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 protoplasm, 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 docs, 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 photo- 

 plasm may exist without a nucleus. 



Under these circumstances it may well be asked, how 

 is one mass of non-nucleated protoplasm to be distin- 

 guished from another ? why call one " plant ' and the 

 other " animal" ? 



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 Mthalium 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 



