146 TKANSAGTIONS AND PUOCEEDINGS OF THE [Sess. Lxvr. 



objections would be valid in cases where in-breeding had 

 taken place ; for Galton's law can only hold good if no 

 in-breeding occur, and if none have happened.' This law 

 really demands that there shall be no in-breeding. 



But there is another aspect of Galton's law, and this 

 arises from the following eml)ryological facts. The reduc- 

 tion of chromosomes was probably, in its origin, merely an 

 undoing of the previous union, and even now it is not the 

 halving of a unit, but of hvo such. Therefore, it is not a 

 reversion to half cells or half entities or individualities, Ijut 

 to whole ones. From this it follows, that at fertilisation 

 we have to deal with the union of two individualities — of 

 two complete lines of ancestry. The union of these is con- 

 tinued in the primary germ-cells, as evidenced Ijy their 

 duplicated nuclei, until the initiation at least of the ensuing 

 determination of sex, and the united lines are l)roken up in 

 two separate complete lines, not necessarily identical (like 

 two strings of many-coloured beads) with the original two 

 at the ensuing sex-determination and reduction." 



All along the line, from the fertilised egg to that primary 

 germ-cell which unfolds as an embryo, this duplication is 

 evident, and, of course, it must at first be in this cell too. 

 As I have recognised in lectures, there must be a competi- 

 tion between the two components of the duplicated nucleus 

 when development begins.^ This will be such, that of the 



' W. K. Brooks has already drawn attention to this matter. He 

 points out that Galton's theory demands absence of relationship among 

 all the ancestors. He then goes on to show that, in the case of three 

 persons living on a small island, their known ancestry goes back seven 

 to eight generations. The maximum number of distinct ancestors for 

 all three persons together should be 1146, according to Brooks. Of 

 these, 452 are recorded, but these are not 452 distinct persons, being, 

 in fact, only 149. ("The Foundations of Zoology," pp. 143-145.) 



- A further discussion of this matter will be found in a memoir upon 

 the Determination of Sex, now in the press {vide "Zool. Jahrb. Morph. 

 Abtheil., 1902 "). 



•' Haecker has quite recently refei'red to this in the following 

 words: — " Eine aehnliche Concurrenz kommt vielleicht audi in den 

 Bildern aus den Gonadanlagen von Diaptomus zum Ausdruck, und 

 wuerde fuer das Verstaendniss mancher Veierbungsert^cheinungen 

 (Dominiren des einen Elter.s) von Bedeutung sein." ( " Anat. Anz.," 

 vol. 20, p. 451.) 



I make no comment whatever upon the foregoing, l)ut leave it to the 

 reader to determine the extent of the agreement between Haecker's 

 brief and vague statement and the idea.s and conclusions developed in 

 the text of the present writing. 



