Identity of Structure of Plants and Animals. 235 



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 nei- 

 ther chemically nor optically homogeneous, but to be com- 

 posed of small definite masses containing a large quantity of 

 nitrogen, imbedded in a homogeneous matrix having a very 

 different chemical composition ; containing in fact abundance 

 of a peculiar substance, Cellulose. 



The nitrogenous bodies may be more or less solid or vesi- 

 cular, and they may or may not be distinguished into a cen- 

 tral mass {nucleus of authors) and a peripheral portion (con- 

 tents, Primordial utricle of authors.) On account of the 

 confusion in the existing nomenclature, the lecturer proposed 

 the term Endoplasts for them. 



The cellulose matrix, though at first unquestionably a 

 homogeneous 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 intercellular substance, 

 being supposed to build up the matrix. On the other hand, 

 the lecturer endeavoured to shew that the existence of sepa- 

 rate 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 physi- 

 cal differences have arisen in the primarily homogeneous 

 matrix, to which, in contradistinction to the endoplast, he 

 proposed to give the name of Periplast or periplastic sub- 

 stance. 



In all 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, con- 

 nective tissue, muscle, epithelium, &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 



