THE PHENOMENA OF ORGANIC NATURE 107 



ditions fitted for their existence ; and though they come 

 into competition, to a certain extent, with one another, 

 the derivative species may not necessarily extirpate the 

 primitive one, or vice versd. 



Now palaeontology shows us many facts which are 

 perfectly harmonious with these observed effects of the 

 process by which Mr. Darwin supposes species to have 

 originated, but which appear to me to be totally inconsistent 

 with any other hypothesis which has been proposed. 

 There are some groups of animals and plants, in the fossil 

 world, which have been said to belong to " persistent types," 

 because they have persisted, with very little change indeed, 

 through a very great range of time, while everything about 

 them has changed largely. There are families of fishes 

 whose type of construction has persisted all the way from 

 the carboniferous rock right up to the cretaceous ; and 

 others which have lasted through almost the whole range 

 of the secondary rocks, and from the lias to the older 

 tertiaries. It is something stupendous this to consider 

 a genus lasting without essential modifications through 

 all this enormous lapse of time while almost everything 

 else was changed and modified. 



Thus I have no doubt that Mr. Darwin's hypothesis 

 will be found competent to explain the majority of the 

 phenomena exhibited by species in nature ; but in an 

 earlier lecture I spoke cautiously with respect to its power 

 of explaining all the physiological peculiarities of species. 



There is, in fact, one set of these peculiar! lies which the 

 theory of selective modification, as it stands at present, 

 is not wholly competent to explain, and that is the group 

 of phenomena which I mentioned to you under the name 

 of Hybridism, and which I explained to consist in the 

 sterility of the offspring of certain species when crossed 

 one with another. It matters not one whit whether this 

 sterility is universal, or whether it exists only in a single 

 case. Every hypothesis is bound to explain, or, at any 

 rate, not be inconsistent with, the whole of the facts 

 which it professes to account for ; and if there is a single 

 one of these facts which can be shown to be inconsistent 

 with (I do not merely mean inexplicable by, but contrary 

 to) the hypothesis, the hypothesis falls to the ground, 

 it is worth nothing. One fact with which it is positively 

 inconsistent is worth as much, and as powerful in negativing 

 the hypothesis, as five hundred. If I am right in thus 



