274 



SCIENCE. 



[Vol. TI., No. 30. 



applicable to the other. Here is a question of ration- 

 al processes, of ordinary reason. If the rules of 

 chemistry are true in America, I imagine they are 

 true in Australia and Africa, although I have not 

 been tliere to see. If the law of gravitation is effec- 

 tive here, I do not need to go to Australia or New 

 Zealand to ascertain whether it is true there. So, 

 if we find in a group of animals a law sufficient to 

 account for their creation, it is not necessary to know 

 that others of their relatives have gone throitgli a 

 similar process. I am willing to allow the ordinary 

 practical law of induction, the practical law of infer- 

 ence, to carry me over these gaps, over these inter- 

 ruptions. And I state the case in that way, because 

 this is just where some people differ from me, and 

 that is just where I say the simple question of ration- 

 ality comes in. I cannot believe that nature's laws 

 are so dissimilar, so irregular, so inexact, that those 

 which we can see and understand in one place are 

 not true in another; and that the question of geo- 

 logical likelihood is similar to the question of geo- 

 graphical likelihood. If a given process is true in 

 one of the geological periods, it is true in another; 

 if it is true in one part of the world, it is true 

 in another; because I find interruptions in tlie 

 series here, it does not follow that there need he 

 interruptions clear through from age to age. The 

 assumption is on the side of that man who asserts 

 tliat transitions have not taken place between forms 

 which are now distinct. 



We are told that we find no sort of evidence of 

 that transition in past geological periods; we are 

 assured that sucli changes have not taken place ; we 

 are even assured that no such sign of such transition 

 from one species to another has ever been observed, 

 — a most astonishing assertion to make to a biolo- 

 gist, or hy a biologist; and such persons have even 

 the temerity to cite special cases, as between tlie wolf 

 and the dog. Many of our domestic dogs are nothing 

 but wolves, whicli have been modified by the hand 

 of man to a very slight extent indeed. Many dogs, 

 in fact, nearly all dogs, are descendants of ^ild 

 species of various countries, and are but slightly 

 modified. 



To take the question of tlie definition of species. 

 Supposing we liave several species well defined, say 

 four or five. In the process of investigation we ob- 

 tain a larger number of individuals, many of which 

 betray clraracters which invalidate the definitions. 

 It becomes necessary to unite the four or five species 

 into one. And so, then, because our system requires 

 that we shall have accurate definitions (the whole, 

 basis of tlie system is definitions: you know the very 

 comprehension of tlie subject requires definitions), 

 we throw them all together, because we cannot define 

 all the various special forms as we did before, until 

 we have but one species. And the critic of the view 

 of evolution tells us, "I told you so! There is but 

 one species, after all. There is no such thing as a 

 connection between species: you never will find it." 

 Now, how many discoveries of this kind will be neces- 

 sary to convince the world that there are coimeclions 

 between species ? How long are we to go on finding 



connecting links, and putting iLem together, as we 

 have to do for the sake of the definition, and then 

 be told that we have, nevertheless, no intermediate 

 forms between species? The matter is loo plain for 

 further comment. We throw them together, simply 

 because our definitions require it. If we knew all 

 the known individuals which have lived, we should 

 have no species, we should have no genera. That is 

 all there is of it. It is simply a question of a univer- 

 sal accretion of material, and the collection of infor- 

 mation. I do not believe that the well-defined groups 

 will be found to run together, as we call it, in any 

 one geological period, certainly in no one recent 

 period. We recognize, however, that they diverge to 

 a wonderful extent: one group has diverged atone 

 period, and another one has become diversified in a 

 different period; and so each one has its history, 

 some beginning farther back than others, some 

 reaching far back beyond the very beginning of the 

 time when fossils could be preserved. I call atten- 

 tion to this view, because it is a very easy matter for 

 us to use words for the purpose of confusing the 

 mind; for, next to the power of language to express 

 clear ideas, is its power of expressing no ideas at 

 all. As we all know, we can soy many things which 

 we cannot think. It is a very easy thing to say 

 twice two is equal to six, but it isampossible to think 

 it. 



I would cite what I mean by variations of species 

 in one of its phases; I would just mention a genus 

 of snakes, Ophibolus, which is found in the United 

 States. If we take the species of this snake-genus 

 as found in the Norlhern States, we have a good 

 many species well defined. If we go to the Gtilf 

 States, and examine our material, we see we have 

 certain other species well defined, and they are very 

 nicely defined and distinguished. If, ]iow, we go to 

 the Pacific coast, to Arizona and New Mexico, we shall 

 find another set of species well defined indeed. If 

 we take all these different types of our specimens of 

 different localities together, our species, as the Ger- 

 mans say, all tumble together: definitions disappear, 

 and we have to recoguize, out of the preliminary list 

 of thirteen or fourteen, only four or five. That is 

 simply a case of the kind of fact with which every 

 biologist is perfectly familiar. 



When we come to the history of the extinct forms 

 of life, it is perfectly true, then, that we cannot 

 observe the process of descent in actual ^operation, 

 because, forsooth, fossils are necessarily dead. We 

 cannot jierceive any activities, because fossils have 

 ceased to act. But if this doctrine be true, we should 

 get the series, if there be such a thing; and we do, 

 as a matter of fact, find longer or shorter series of 

 structures, series of organisms proceeding from one 

 thing into another form, which are exactly as they 

 ought to be if this process of development by de- 

 scent had taken place. 



I am careful to say this; because it is literally true, 

 as we all must admit, that the system must fall into 

 some kind of order or other. Yon could not collect 

 bottles, you could not collect old shoes, but you 

 could make some kind of a serial order of them. 



