1853.] OF THE ROYAL INSTITUTION. 299 
contrasted with beings which do not live; and it was to the essen- 
tial nature of organization that the Lecturer on the present occasion 
desired to direct attention. 
An organized body does not necessarily possess organs in the 
physiological sense—parts that is, which discharge some function 
necessary to the maintenance of the whole. Neither the germ nor 
the lowest animals and plants possess organs in this sense, and yet 
they are organized. 
It is not mere external form, again, which constitutes organization. 
On the table there was a lead-tree (as it is called) which, a mere 
product of crystallization, possessed the complicated and graceful 
form of a delicate Fern. If a section were made of one of the 
leaflets of this tree, it would be found to possess a structure optically 
and chemically homogeneous throughout. 
Make a section of any young portion of a true plant, and the result 
will be very different. It will be found to be neither chemically 
nor optically homogeneous, but to be composed of small definite 
masses containing a large quantity of nitrogen, imbedded in a homo- 
geneous matrix having a very different chemical composition; con- 
taining in fact abundance of a peculiar substance — Cellulose. 
The nitrogenous bodies may be more or less solid or vesicular — 
and they may or may not be distinguished into a central mass (nucleus 
of Authors) and a peripheral portion (Contents, Primordial utricle 
of Authors) — on account of the confusion in the existing nomen- 
- clature, the Lecturer proposed the term Endoplasts for them. 
The cellulose matrix, though at first unquestionably a homoge- 
neous continuous substance, readily breaks up into definite portions 
surrounding each Endoplast ; and these portions have therefore 
conveniently, though, as the Lecturer considered, erroneously, been 
_ considered to be independent entities under the name of Cells: — 
these, by their union, and by the excretion of a hypothetical inter- 
cellular substance, being supposed to build up the matrix. On 
the other hand, the Lecturer endeavoured to shew that the exist- 
ence of separate cells is purely imaginary, and that the possibility 
of breaking up the tissue of a plant into such bodies, depends simply 
upon the mode in which certain chemical and physical differences have 
arisen in the primarily homogeneous matrix, to which, in contra- 
distinction to the Endoplast, he proposed to give the name of peri- 
plast or periplastic substance. 
In al] young animal tissues the structure is essentially the same, 
consisting of a homogeneous periplastic substance with imbedded 
Endoplasts (nuclei of Authors); as the Lecturer illustrated by reference 
to diagrams of young Cartilage, Connective tissue, Muscle, Epithe- 
lium, &c. &c.; and he therefore drew the conclusion that the 
common structural character of living bodies, as opposed to those 
which do not live, is the existence in the former of a local physico- 
chemical differentiation ; while the latter are physically and chemi- 
cally homogeneous throughout. 
These facts, in their general outlines, have been well known 
