CHAPTER XIV. 



ON THE NATURE AND BASIS OF HEREDITY. 



Parts of two addresses and a considerable amount of less closely written mate- 

 rials have been seriated by the editor to form the present chapter. The 1 hive groups 

 of materials are here placed in the order of their preparation, and under their 

 original titles. 



HEREDITY.* 



The subject of heredity covers a wide field, and the central problem has been 

 scarcely more than located. It has long been obscured with traditional myths, 

 which, like other traditions, often live in one disguise or another after they have been 

 repudiated. One of these myths, if one may venture to so classify it, is the idea that 

 heredity stands for "transmission," with emphasis placed on the irons. 



The Century Dictionary defines heredity as "the influence of parents upon 

 offspring; transmission of qualities or characteristics, mental or physical, from parents 

 to offspring." The essential idea here is contained in the word "transmission." 

 The characters of the offspring are conceived of as inherited, as if they represented 

 elements that belonged primarily to the parents and were by them bequeathed as 

 legacies to their children. 



We may flatter ourselves that we have completely outgrown such a crude con- 

 ception, but the traditional term continues in everyday use, and the traditional 

 idea still cleaves to it. Witness the belief still held by a considerable number of 

 naturalists which not long ago was so ably championed by Herbert Spencer and as 

 ably controverted by Weismann the belief handed down from Lamarck, that, 

 "characters" functionally acquired during the lifetime of the parents are trans- 

 missible to the offspring. 



Darwin's pangenesis and the intracellular pangenesis of de Vries represent 

 elaborate systems of transmission, in which the central myth expands into a train 

 of ancillary myths, each designed to conceal the weakness of the mother myth. 

 Darwin ends his discussion of pangenesis with the following words: 



"Each living creature must be looked at as a microcosm a little universe, formed of a host of 

 self-propagating organisms, inconceivably minute and as numerous as the stars of heaven"' 

 (Animals and Plants, u, p. 483). 



Darwin's hypothesis represented the germ-cells as composed of these "hosts of 

 self -propagating " pangens, collected from every point in the body. Think of these 



1 The manuscript treating of this topic represents that portion of a lecture at Woods Hole, July 29, 1907, that 

 was reduced to writing (SS 12). It is given first position in this chapter because of its consideration of the more 

 general aspects of development. The method of treating the subject, adopted by the author in these pages, suggests 

 that this material more properly belongs with the chapters on Orthogenetic Evolution, in Volume I. But the fact 

 that three quite different aspects of heredity are considered in these three groups of materials led to the conclusion 

 that no one of the three aspects of the subjects should be presented as an isolate. The two additional parts of the 

 chapter are: A part of a lecture (on Mendelian heredity), of February 28, 1908, before the Wisconsin Natural History 

 Society (Z5), and, finally some short, sketchy materials (R 10, W\V 1, EM 9, W 9) which the author had not yet 

 arranged in final manuscript form, but which constitute his last writings and conclusions on matters of much 

 interest to the present volume, chiefly on "germinal weakness" and evidences of it and of its modifiahility. ED. 



1 This passage is adopted by de Vries as a motto to adorn the title page of his " Intra-ccllular Pangenesis." 



177 



