PEESENT PROBLEMS IN EVOLUTION AND HEREDITY.* 



By Henry Faiei'ield Osborn. 



In the past decade of practii-al research and S])ecn]ation in biology, 

 two snbjects have oustripped in interest and importance the rapid prog- 

 ress all along the line. These are, tirst, the life history of the repro- 

 ductive cell from its infancy in the ovum onward, and second, the 

 associated problem of heredity, which passes insensibly from the held 

 of direct observation into the region of pure speculation. 



As regards the cell it was generally believed that the nucleus was an 

 arcannm into the mysteries of which we could not far penetrate; but 

 this belief has long been dispelled by the eager specialist, and it is no 

 exaggeration to say that we now know more about the meaning of the 

 nucleus than we did about the entire cell a few years ago. At that 

 time the current solution of the heredity problem was a purely formal 

 one; it (;ame to the main barrier, namely, the relation of heredity and 

 evolution to the reproductive cells, and leapt owv it by the postulate 

 of Pangenesis. The germ-cell studies of Balfour, Van Beneden, the 

 Hertwig brothers, Weismann, Boveri, and others, have gradually led 

 us to hope that we shall sonu' day trace the connection between the 

 intricate metamorphos(\s in these cells and the external phenomena of 

 heredity, and more than this, to realize that the heredity theory of the 

 future must rest upon a far more exact knowledge than we enjoy at 

 present of the history of the reproductive cell both in itself and in the 

 influence which the surrounding body cells lia\<' upon it. 



These advances alfe(;t the problem of lil'e and proto])lasm, whether 

 studied by the ])hysician, the antiiropologist, or the zoologist, thus con- 

 centrating into one focus o])inions wliicli ha\ e been formed by the 

 observation of widely different (glasses of facts. As each class of facts 

 bears to the observ(;r a diifei'ent aspect and gives him a i)ersonal bias, 

 the discusson is by no means irenical, and it is our i)iivilege to live 

 through one of those heated ]>eriods which mai'k the course of every 

 revolution in the world of ideas. Such a crisis was brought about bv 



*The Cartvvright Lectures for 1892; delivered before Ahiiimi of tli«^ College of 

 Physicians ami Surgeons, l\'hiuar.\' 12. 19, and 26, 1892. (From tlu^ Medical lUrord 

 for February 20, March .■"), April 28, an<l May 11, 1892.) 



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