BIOLOGICAL WRITINGS OF SAMUEL BUTLER 23 



The last of Butler's biological writings is the essay, The 

 Deadlock in Darwinism, containing much valuable criticism 

 of Wallace and Weismann. It is in allusion to the misnomer 

 of Wallace's book, Darivinisiu, that he introduces the term 

 " Wallaceism " ^ for a theory of descent that excludes the 

 transmission of acquired characters. This, indeed, was the 

 chief factor that led Charles Darwin to invent his hypothesis 

 of pangenesis, which, unacceptable as it has proved, had far 

 more to recommend it as a formal hypothesis than the equally 

 formal germ-plasm hypothesis of Weismann. 



The chief difficulty in accepting the main thesis of Butler 

 and Hering is one familiar to every biologist and not at all 

 difficult to understand by the layman. Every one knows that 

 the complicated beings that we term "Animals" and "Plants" 

 consist of a number of more or less individualised units, the 

 cells, each analogous to a simpler being, a Protist — save in so 

 far as the characters of the cell unit of the Higher being is 

 modified in accordance with the part it plays in that complex 

 being as a whole. Most people, too, are familiar with the fact 

 that the complex being starts as a single cell, separated from 

 its parent, or, where bisexual reproduction occurs, from a 

 cell due to the fusion of two cells, each detached from its 

 parent. Such cells are called " Germ-cells." The germ-cell, 

 whether of single or of dual origin, starts by dividing re- 

 peatedly, so as to form the primary embryonic cells, a complex 

 mass of cells, at first essentially similar, which, however, as 

 they go on multiplying, undergo differentiations and migra- 

 tions, losing their simplicity as they do so. Those cells that 

 are modified to take part in the proper work of the whole 

 are called tissue-cells. In virtue of their activities, their 

 growth and reproductive power are limited — much more in 

 Animals than in Plants, in Higher than in Lower beings. It 

 is these tissues, or some of them, that receive the impressions 

 from the outside which leave the imprint of memory. Other 

 cells, which may be closely associated into a continuous organ 

 or more or less surrounded by tissue-cells whose part it is 

 to nourish them, are called " secondary embryonic cells " or 

 " germ-cells." The germ-cells may be differentiated in the 



* The term has recently been revived by Prof. Hubrecht and by myself 

 {Contemporary Review, November 1908). 



