172 THE CONTINUITY OF THE GEBM-PLASM AS THE 



up the parent's body, and the germ-cells of succeeding generations 

 stand in a similar relation to one another as a series of generations 

 of unicellular organisms, arising by a continued process of cell- 

 division. It is true that in most cases the generations of germ-cells 

 do not arise immediately from one another as complete cells, but 

 only as minute particles of germ-plasm. This latter substance, 

 however, forms the foundation of the germ-cells of the next genera- 

 tion, and stamps them with their specific character. Previous to 

 the publication of my theory, G. Jager *, and later M. Nussbaum 2 , 

 have expressed ideas upon heredity which come very near to my 

 own 3 . Both of these writers started with the hypothesis that there 



1 Jager, ' Lehrbuch der allgemeinen Zoologie,' Bd. II. Leipzig, 1878. 



a M. Nussbaum, ' Die Differenzirung des Geschlechts im Thierreich,' Arch. f. 

 Mikrosk. Anat., Bd. XVIII. 1880. 



3 I have since learnt that Professor Rauber of Dorpat also expressed similar 

 views in 1 880 ; and Professor Herdman of Liverpool informs me that Mr. Francis 

 Galton had brought forward in 1876 a theory of heredity of which the fundamental 

 idea in some ways approached that of the continuity of the germ-plasm (' Journal 

 of the Anthropological Institute,' vol. v ; London, 1876). A. W., 1888. 



[A less complete theory was brought forward by Galton at an earlier date, in 

 1872 (see Proc. Roy. Soc. No. 136, p. 394). In this paper he proposed the idea that 

 heredity chiefly depends upon the development of the offspring from elements directly 

 derived from the fertilized ovum which had produced the parent. Galton speaks of 

 the fact that ' each individual may properly be conceived as consisting of two parts, 

 one of which is latent and only known to us by its effects on his posterity, while the 

 other is patent, and constitutes the person manifest to our senses. The adjacent and, 

 in a broad sense, separate lines of growth in which the patent and latent elements 

 are situated, diverge from a common group and converge to a common contribution, 

 because they were both evolved out of elements contained in a structureless ovum, 

 and they, jointly, contribute the elements which form the structureless ova of their 

 offspring.' The following diagram shows clearly 'that the span of each of the links in 

 the general chain of heredity extends from one structureless stage to another, and 

 not from person to person : 



Structureless elements ( ... Adult Father ... 1 structureless elements 



in Father ( ... Latent in Father . . . j in Offspring.' 



Again Galton states ' Out of the structureless ovum the embryonic elements are 

 taken . . . and these are developed (a) into the visible adult individual ; on the 

 other hand . . ., after the embryonic elements have been segregated, the large 

 residue is developed (i) into the latent elements contained in the adult individual.' 

 The above quoted sentences and diagram indicate that Galton does not derive the 

 whole of the hereditary tendencies from the latent elements, but that he believes 

 some effect is also produced by the patent elements. When however he contrasts 

 the relative power of these two influences, he attaches comparatively little importance 

 to the patent elements. Thus if any character be fixed upon, Galton states that it 

 ' may be conceived (i) as purely personal, without the concurrence of any latent 

 equivalents, (2) as personal but conjoined with latent equivalents, and (3) as existent 

 wholly in a latent form.' He argues that the hereditary power in the first case is 



