Appendix to Chapter V. 439 



the burden of proof is thrown upon those who point to par- 

 ticular cases where there is thus a conspicuous absence of 

 transitional forms the burden, namely, of proving that such 

 cases are not due merely to a break in the record. Besides, 

 the break in the record as regards this particular case may 

 be apparent rather than real. For I suppose there is no 

 greater authority on the. pure geology of the subject than 

 Sir Charles Lyell, and this is what he says of the particular 

 case in question. " If the passage seem at present to be 

 somewhat sudden from the flora of the Lower or Neocomian 

 to that of the Upper Cretaceous period, the abruptness of 

 the change will probably disappear when we are better ac- 

 quainted with the fossil vegetation of the uppermost tracts of 

 the Neocomian and that of the lowest strata of the Gault, or 

 true Cretaceous series V 



Lastly, the fact of the flora of the glacial epoch not 

 having exhibited any modifications during the long residence 

 of some of its specific types in Great Britain and else- 

 where, is a fact of some importance to the general theory of 

 evolution, since it shows a higher degree of stability on the 

 part of these specific types than might perhaps have been ex- 

 pected, supposing the theory to be true. But I do not see that 

 this constitutes a difficulty against the theory, when we have so 

 many other cases of proved transmutation to set against it. 

 For instance, not to go further afield than this very glacial 

 flora itself, it will be remembered that in an earlier chapter 

 I selected it as furnishing specially cogent proof of the 

 transmutation of species. What, then, is the explanation of 

 so extraordinary a difference between Mr. Carruthers' views 

 and my own upon this point ? I believe the explanation to 

 be that he does not take a sufficiently wide survey of the 

 facts. 



To begin with, it seems to me that he exaggerates the 

 vicissitudes to which the species of plants that he calls into 

 1 Elements of Geology, p. 280. 



