68 
GARDENING AS A SCIENCE. 
think is almost proved to be electricity,) the plant, from its infancy, absorbs food, 
and laborates or digests it in a way conformable to its individual constitution. 
All the laborating or vitalized parts of the plant are therefore present in and from 
the earliest rudiments of the seed ; all are fed, and in proportion become enlarged, 
but- not one is subsequently created. On the other hand, all the nutrimental 
substances attracted into the cells, however duly assimilated, never become organs ; 
they are merely matters which supply the wants of the vegetable, as bread supplies 
the demands of the human frame. Hence the art of man can only induce stimulus, 
arid must entirely fail to add one individual vitalized atom to the organic structure. 
Whatever particles, therefore, a plant attracts, may be considered nutrimental ; 
whatever it rejects, whether through the exudatory organs of the root, or by the 
stomates of the foliage, must be deemed fecal. 
The . following extracts from Mr. Main s ^Illustration of Vegetable Vhysiology 
are extremely apposite, and perhaps incapable of refutation. 
44 Every developed member of a tree is imbued with the vital principle in its early 
existence, and retains it while in the act of expansion, but no longer. There are 
two states or degrees of vegetable life. The first is always present in those 
members which are capable of amplification, or are in the act of accretion, i. e. 
expanding from a small to a large volume. The second is that state in which it is 
only conservative, but without the power of a further growth of the members 
preserved by it. The first, it is deemed proper to designate by the name of vital 
envelope, whence proceeds every new member of trees, shrubs, and many herbaceous 
plants." 
" This slender body of vitality, or vital envelope, is constitutionally compound, 
.not simple, as such a thin tissue may be supposed to be ; containing the rudiments 
of both roots and buds ; and, moreover, is the source of all accretion, whether as 
to magnitude or number of parts produced. 
" The foregoing idea of the existence of a distinct vital member, whence all new 
accretions proceed, is directly opposed to the modern doctrine of the 4 organizable 
property ' of the elaborated sap of plants. The idea is founded upon the general 
law of vegetable nature, for where do we find the most insignificant vegetable body 
come into existence without having a pre-existing embryo or rudimental atom, 
whence it derives its essential structure and qualities ? There is no such instance 
in nature. Can the most minute species of Fungi spring forth without its 
propago, or the smallest herb without a seed, or previously existing part of 
itself? Is the bark or wood self-productive ? No ; when either is destroyed, it 
cannot be renewed but by the assistance of the vital member which is the origin of 
both." 
As Mr. Main's theory so far is based upon the development of the new layer 
of wood and bark which is annually made through the medium of the vital membrane, 
generally called Cambium, he dwells almost exclusively upon those developments. 
One paragraph in reference to buds must not be overlooked. 
