ON THE VITALISTIC VIEW OF NATURE. 459 



perishable, mortal, doomed, after temporarily serving the 

 purposes of individual development, to disappear from 

 the category of living matter. 



And secondly, it appears that the germinal substance M- 



J ' Differentia 



or germ - plasma, when once differentiated from the p^^ f a g 

 personal substance or body-plasma, cannot, as a rule, 

 perform unaided the function of continuous preservation 

 of the species or phylum. In all the higher animals 

 the germ -substance appears in two distinct seemingly 

 complementary forms, and only by the fusion of these 

 does the development of the germ -substance become 

 possible. 



The great difficulties which stand in the way of 

 applying these conceptions (which have found an ex- 

 haustive exposition in Prof. Weismann's ' Essays on 

 Descent and Heredity ') to the vegetable kingdom have 

 been pointed out, and have prevented their general 

 adoption by biologists ; l nor have the elaborate modifi- 

 cations introduced in Prof. Weismann's later writings 

 tended to make them more acceptable ; the idea, never- 

 theless, of a fundamental differentiation of the elements 

 of living matter into germinal and personal has got hold 

 of the scientific mind at the present day, and cannot be 



1 On the objections of Prof. Stras- 

 burger, who points to the fact that 

 in the case of begonias the frag- 

 ment of a leaf planted in moist sand 

 can reproduce the whole plant ; of 

 Prof. Vines, who shows that whole 

 groups of cham pign ons, wh ich propa- 

 gate annually, are nevertheless rich 

 in genera and species, which have 

 evidently descended from one an- 

 other, see Yves Delage, 'L'He're'dite',' 



Problem of To-day,' transl. by P. 

 C. Mitchell (1896), p. 40, &c. On 

 the discovery of Weismann ' ' that 

 in parthenogenetic ova only one 

 polar globule is formed, while there 

 are always two in ova which are 

 impregnated," and the "moment- 

 ary " presumption in favour of his 

 theory which it afforded, see ' Essays 

 on Heredity,' p. 333, &c. ; Geddes 

 and Thomson, ' Evolution of Sex,' 



p. 526, Ac. ; ' Nature,' vol. x. p. 621 ; p. 180, &c. ; and Delage, ' L'Hdre"- 

 also 0. Hertwig, 'The Biological diteV p. 151. 



