ZOOLOGY 



ON THE IDENTITY OF STRUCTURE OF PLANTS AND ANIMALS. 



The folloAving is an abstract of a recent paper read before the Royal 

 Institution England, by T. H. Huxley, Esq. The author commenced 

 by referring to the researches of Schleiden and Schwann, upon 

 the structure, functions and developement of the cells in plants and 

 animals. Admitting to the fullest extent the service which the 

 cell-theory of Schleiden and Schwann had done in anatomy and 

 physiology, he endeavored to show that it was nevertheless infected 

 by a fundamental error, which had introduced confusion into all 

 later attempts to compare the vegetable with the animal tissues. 

 This error arose from the circumstance that when Schwann wrote, the 

 primordial utricle in the vegetable cell was unknown. Schwann, 

 therefore, who started in his comparison of animal with vegetable 

 tissues from the structure of cartilage, supposed that the corpuscle of 

 the cartilage cavity was homologous with the " nucleus " of the vege- 

 table cell, and that therefore all bodies in animal tissues homologous 

 with the cartilage corpuscles were u nuclei." The latter conclusion is 

 a necessary result of the premises ; and therefore the lecturer stated 

 that he had carefully re-examined the structure of cartilage, in order 

 to determine which of its elements corresponded with the primordial 

 utricle of the plant, the important missing structure of which 

 Schwann had given no account: working subsequently from cartil- 

 age to the different tissues with which it may be traced into direct or 

 indirect continuity, and thus ascertaining the same point for them, the 

 general result of these investigations may be thus expressed: in all 

 the animal tissues the so-called nucleus (endoplast) is the homologue 

 of the primordial utricle (with nucleus and contents) (endoplast) of 

 the plant, the other histological elements being invariably modifications 

 of the periplastic substance. Upon this view we find that all the 

 discrepancies which had appeared to exist between the animal and 

 vegetable structures disappear, and it becomes easy to trace the 

 absolute identity of plan in the two, the differences between them 

 being produced merely by the nature and form of the deposits in, or 

 modifications of, the periplastic substance. After referring to the 

 various chemical and morphological changes undergone by the periplast 

 and endoplast, the lecturer stated that in both plants and animals there 



