ioo SCIENCE PROGRESS. 



of cells ; (2) that the cause of nutrition and growth resides 

 not in the organism but in its separate elementary parts. 



The attacks which have recently been directed against 

 the cell-theory may be resolved into contradictions of these 

 two fundamental propositions. On the one hand there is 

 the considerable number of cytologists, whose opinions 

 may be taken to be summed up in Whitman's essay on 

 the inadequacy of the cellular theory, who deny the second 

 proposition, and in so doing implicitly deny the truth of 

 the first. They would say that the cause of nutrition and 

 growth does not reside in the cells considered as elementary 

 parts, but in parts still more elementary, the ultimate vital 

 units of which the cells themselves are composed. On 

 the other hand Mr. Adam Sedgwick denies the first pro- 

 position in toto. He states boldly that the elementary 

 parts of tissues are not formed of cells, but of a continuous 

 mass of vacuolated protoplasm containing nuclei. 1 These 

 objections, though they are raised from different stand- 

 points, are not irreconcilable, but it will be convenient to 

 deal with them separately. First let us consider the 

 objections to the cell as an ultimate vital unit. 



These objections are of long standing. They were first 

 brought forward by Briicke 2 in 1861 ; 3 not long afterwards 



1 Since this was written Mr. Sedgwick has published a further account 

 of his views, which makes it necessary to modify this statement. See 

 infra. 



2 Ernst Briicke, " Die Elementarorganismen," Sitzungsberichte der K. 

 Akademie der Wissenschaften, Wien, bd., xliii., p. 381, 1861. 



3 Delage points out that the merit of regarding protoplasm as an 

 organised substance belongs to Dujardin, and not to Brucke. At the 

 same time he points out the essential difference between Briicke's concept 

 of organisation and that of Dujardin, greatly to the advantage of the latter : 

 " La difference entre Dujardin et Brucke est tres simple. Le premier a 

 devine l'existence de structures que le microscope demontre aujourd'hui ; 

 tandis qu'en introduisant dans la conception de protoplasma cette notion 

 acceptee avec enthousiasme, d'organismes tres compliques et invisibles, 

 Brucke a ouvert la porte aux nombreuses theories speculatives qui cher- 

 chent a imaginer la structure de ces organismes pour expliquer par elles les 

 phenomenes de la vie." Delage adopts the expression organisation, saying : 

 " Le protoplasme n'est pas simplement, comme on l'a cru longtemps, une 

 substance chimique organique, mais il est organise, c'est-a-dire possede une 



