IV] OF THE CELL-THEORY 341 



portance of one or other; but because we are so much in the dark 

 as to the mysterious field of force in which the chromosomes he, 

 far from the visible horizon of physical science, that the matter lies 

 (for the present) beyond the range of problems which this book 

 professes to discuss, and the trend of reasoning which it endeavours 

 to mamtain. 



The cell*, which Goodsir spoke of as a centre of force, is in reality 

 a sphere of action of certain more or less localised forces; and of 

 these, surface-tension is the particular force which is especially 

 responsible for giving to the cell its outline and its morphological 

 individuahty. The partially segmented differs from the totally 

 segmented egg, the unicellular Infusorian from the minute multi- 



* The " cell -theory " began early and grew slowly. In a curious passage which 

 Mr Clifford Dobell has shewn me {Nov. Org. ii, 7, ad fin.). Bacon speaks of "cells" 

 in the human body: of a " coUocatio spiritus per corpoream molem, eiusque pori, 

 meatus, venae et cellulae, et rudimenta sive tentamenta corporis organici." It is 

 " surely one of the most strangely prophetic utterances which even Bacon ever 

 made." Apart from this the story begins in the seventeenth century, with Robert 

 Hooke's well-known figure of the "cells" in a piece of cork (1665), with Grew's 

 "bladders" or "bubbles" in the parenchyma of young beans, and Malpighi's 

 "utriculi" or "sacculi" in the parenchyma or "utriculorum substantia" of 

 various plants. Christian Fr. v. Wolff conceived, about the same time, a hypo- 

 thetical "cell-theory," on the analogy of Leibniz's Monads; but the first clear 

 idea of a cellular parenchyma, or contextus cellularis, came from C. Gottlieb 

 Ludwig (1742), and from K. Fr. Wolff, who spoke freely of cells or cellulae. 

 Fontana, author of a curious Traite sur le venin de la vipere (1781), described 

 various histological elements, caught a glimpse of the nucleus, and experi- 

 mented with reagents, using syrup of violets for a stain. Early in the 

 eighteenth century the vessels of the plant played an important role, under Kurt 

 Sprengel and Treviranus; but it was not till 1831 that Hugo v. Mohl recognised 

 that they also arose from "cells." About this time Robert Brown discovered, 

 or re-discovered, the nucleus (1833), which Schleiden called the cytohlast, or "cell- 

 producer." It was Schleiden's idea, and a far-seeing one, that the cell lived a double 

 life, a life of its own and the life of the plant to which it belonged: "jede Zelle 

 fuhrt nun ein zweifaches Leben : ein selbststandiges, nur ihrer eigenen Entwicklung 

 angehorigen, und ein anderes mittelbares, insofern sie integrierender Theil einer 

 Pfianze geworden ist " {Phylogenesis, 1838, p. 1 ). The cell-theory, so long a- building, 

 may be said to have been launched, and christened, with Schwann's Mikroskopische 

 Untersmhungen of 1839. Within the next five years Martin Barry shewed how 

 cell-division starts with the nucleus, Henle described the budding of certain cells, 

 and Goodsir declared that all cells originate in pre-existing cells, a doctrine at once 

 accepted by Remak, and made famous in pathology by Virchow. (Cf. {int. al.) 

 J. G. McKendrick, On the modern cell-theory, etc., Proc Phil. Soc. Glasgow, xix, 

 pp. 1-55, 1887; J. Stephenson, Robert Brown. . .and the cell-theory, Proc. Linn. 

 Soc. 1931-2, pp. 45-54; M. Mobius, Hundert Jahre Zellenlehre, Jen. Ztschr. lxxi, 

 pp. 313-326, 1938.) 



