Appendixes 32 1 



as a working h3'pothesis, and then represent normal sight 

 by N, colour-bhndness by absence or modihcation of 

 N ( = ?0' ^^^ further suppose that N can only be borne 

 by gametes containing a sex-determiner (^ or $, not O), we 

 obtain the observed results." 



Facts bearing on the general theory of sex-determination 

 have accumulated so fast that they would require a separate 

 treatise for adequate enumeration and discussion. Reference 

 can here be made to one group of experiments alone, those 

 of Goldschmidt (^Zts, indukt. Abstain., 191 2, vii. p. i), in 

 which phenomena of extraordinary novelty and significance 

 are recorded. The most striking experiment was that in 

 which the moths Lyniantria dispar and japoiica were 

 reciprocally crossed. 



L. Japonica $ x dispa7^ $ gives constantly both sexes 

 hybrid, showing mixture of the parental characters. 



The reciprocal, L. dispar $ y. japonica ^, gives families 

 which at first sight seem to be all males, but on closer 

 examination it is found that in reality they consist of nonual 

 males and gynandromorplis having the characters of the 

 sexes mixed in various degrees. From these gynandro- 

 morphs it was however possible to breed, and subsequent 

 generations were obtained from both types of crosses. The 

 results were complex and difficult to interpret, but an 

 analysis of great interest is suggested by Goldschmidt. 



In connexion with this paper reference should be made 

 to another curious series of results obtained by Kuttner 

 {Intern. Rev. Gesamt. HydrobioL, 11. 1909) in an investi- 

 gation of the descent of sex In Daphnia. In this case 

 also the descent from certain peculiar forms called "pseudo- 

 hermaphrodites" was studied. Actual hermaphrodites re- 

 garded as originally females and others regarded as originally 

 males occurred in these series. The numbers obtained were 

 considerable, but as yet no satisfactory analysis has been 

 made. 



Appendix to Chapter XL 



Two important contributions to the Investigation of the 

 genetics of doubleness have been made by Miss Saunders. 

 A factorial analysis is provided by which the descent of 



B. H. 21 



