DOCTRINE OF ORGANIC EVOLUTION 439 



If we trace the evolution of a given form backward to its 

 beginning we come to more and more primitive conditions. 

 Mouse-tails, for example, we should derive from ancestors re- 

 sembling buttercups in having a shorter torus, more stamens, 

 spurless staminodes, and broader leaves. It seems reasonable 

 to suppose that these mouse-tail-buttercups left no unmodified 

 descendants, and so were not exactly like any living form of 

 buttercup, although we might fairly presume that they 

 showed more of the relatively primitive buttercup structure 

 than of the peculiar mouse-tail features. These buttercup-like 

 ancestors would be traced back to progenitors more nearly 

 resembling anemonies in which rudimentary ovules still bore 

 witness to a previous many-ovuled stage, when also certain 

 of the outer stamens were showing only rudimentary anthers 

 and were secreting nectar on broadened filaments. The 

 step from this form, from which both mouse-tails and anem- 

 onies descended, to the marsh-marigold-like ancestors of the 

 family, requires us to imagine little more than a previous full 

 development of the ovules and anthers which later became 

 reduced, and a more ordinary form of filaments and carpels. 



In the above examples of the way an evolutionist conceives 

 the changes in a group to have progressed, innumerable 

 details of the process have necessarily been omitted for the 

 sake of simplicity. jNIany branches would have to be inter- 

 polated if all living genera of the family were to be repre- 

 sented, and there is no knowing how many dead branches 

 should be shown to make the family tree complete. It must, 

 of course, be frankh^ admitted that the conclusions are largely 

 guesswork supported only by circumstantial evidence, for 

 no remains of the very perishable ancestral forms of the 

 crowfoot family have come to light. Our examples, however, 

 are typical of evolutionary schemes in general, and so may 

 help our understanding of the theory' of evolution. One 

 prevalent misconception which it should correct is the notion 

 that forms now living are supposed to have been derived from 

 ancestors just like other recent forms. On the contrary, 



the kind of conclusions they reach by such means. That such conclu- 

 sions are at best far from satisfactory goes without saying; but herein 

 lies a challenge to do better, and a spur to further study. 



