Polytechnic Association. 803 



Schwann burdened his enunciation of the " cell theory " with two 

 false suppositions ; the one, that the structures he called " nucleus " 

 and " cell-wall " are essential to a cell ; the other, that cells are usually 

 formed independently of other cells ; but, in 1839, it was a vast and 

 clear gain to arrive at the conception, that the vital functions of all 

 the higher animals and plants are the resultant of the forces inherent 

 in the innumerable minute cells of which they are composed, and that 

 each of them is, itself, an equivalent of one of the lowest and sim- 

 plest of independent living beings — the Toru 7 a. 



From purely morphological investigations, Turpin and Schwann, 

 as we have seen, arrived at the notion of the fundamental unity of 

 structure of living beings. And, before long, the researches of the 

 chemists gradually led up to the conception of the fundamental unity 

 of their composition. 



So far back as 1803, Thenarcl pointed out, in most distinct terms, 

 the important fact that yeast contains a nitrogenous " animal " sub- 

 stance ; and that such substance is contained in all ferments. Before 

 him, Fabroni and Fourcroy speak of the u vegeto-animal " matter of 

 yeast. In 1844 Mulder endeavored to demonstrate that a peculiar 

 substance, which he called " protein," was essentially characteristic of 

 living matter. 



In 1846, Payen writes : 



" Enfin, une loi sans .exception me semble apparaitre dans les faits 

 nombreux que j'ai observes et conduire a envisager sous un nouveau 

 jour la vie vegetale ; si je ne m'abuse, tout ce que dans les tissus vege- 

 taux la vue directe ou amplified nous permet de discerner sous la forme 

 de cellules et de vaisseaux, ne represente autre chose que les envel- 

 oppes protectrices, les reservoirs et les conduits, a l'aide desquels les 

 corps animes qui les secretent et les fac^onnent, se logent, puisent et 

 charrient leurs alimens, deposent et isolent les matieres excretees." 



And again : 



"Aim de completer aurjourd'hui Fenonce du fait general, je rap- 

 pellcrai que les corps, doue des fonctions accomplies dans les tissus 

 des plantes, sont formes des elemens qui constituent, en proportion 

 peu variable, les organismes animaux; qu'ainsi l'on est conduit a 

 reconnaitre une immense unite de composition elementaire dans tons 

 les corps vivants de la nature."* 



In the year (1846) in which these remarkable passages were pub- 

 lished, the eminent German botanist, Yon Mohl, invented the word 

 " protoplasm " as a name for one portion of those nitrogenous con- 



* Mem. sur les Devcloppemcnt^ de* Vegetans, etc. Mem. Presentees, ix. 184G. 



