INCOMPLETENESS OF THE CELL THEORY. 21 



was accepted for many years in medicine ; the cell being in the 

 words of Virchow " the ultimate morphological unit in which 

 there is any manifestation of life." The development of cells 

 form a free blastema was again favoured by Todd and Bowman 

 in 1856, but since the adoption of Goodsir's proposition by 

 Virchow, it has been finally abandoned, and the aphorism of 

 that author omnis cellula e celluld has been substantially ac- 

 cepted by all. It must be borne in mind that while the non- 

 essentiality of the cell wall to the completeness of the cell was 

 generally accepted, nevertheless, as yet, no one had distinctly 

 denied to it in all cases the participation in truly vital functions 

 when present, and it is especially to the cell membrane that 

 Schwann attributes the power he first named metabolic, and 

 which it is here proposed to accept as synonymous with vital. 



By the cell theory, we have thus arrived at a system 

 by which " every animal presents itself as a sum of 

 vital unities, any one of which manifests all the cha- 

 racteristics of life " (Virchow, p. 13). Likewise the 

 specific characters of the life of each part is inherent 

 in these unities themselves, and is not assigned to them 

 by any central life or power of a spiritual or other 

 nature. Nor can anything of the nature of life be 

 communicated from one of these unities to another 

 except by way of growth and subdivision. By the 

 general acceptance of this theory the first of the prin- 

 ciples contended for by Fletcher is thus seen to be 

 established, and the hypothesis of a single central 

 vital principle, or anima, or spirit which gives the 

 unity and vital character to individuals in the animal 

 kingdom is shown to be superfluous and inconsistent 

 with the facts. As observed by Schwann, " the 

 wbole organism subsists only by means of the re- 

 ciprocal action of the single elementary parts " the 



