18701882] G ALT ON 361 



(3) If gemmules (to use my own term) were often Letter 271 

 deficient in buds, I cannot but think that bud-variations 



would be commoner than they are in a state of nature ; nor 

 does it seem that bud-variations often exhibit deficiencies 

 which might be accounted for by the absence of the proper 

 gemmules. I take a very different view of the meaning or 

 cause of sexuality. 1 



(4) I have ordered Eraser's Magazine? and am curious 

 to learn how twins from a single ovum are distinguished 

 from twins from two ova. Nothing seems to me more 

 curious than the similarity and dissimilarity of twins. 



(5) Awfully difficult to understand. 



(6) I have given almost the same notion. 



(7) I hope that all this will be altered. I have received 

 new and additional cases, so that I have now not a shadow 

 of doubt. 



(8) Such cases can hardly be spoken of as very rare, as 

 you would say if you had received half the number of cases 

 I have. 3 



I am very sorry to differ so much from you, but I have 



sexes, because swarms of creatures of the simplest organisations mainly 

 multiply by some process of self-division." 



1 Mr. Gallon's idea is that in a bud or other asexually produced part, 

 the germs (i.e. gemmules) may not be completely representative of the 

 whole organism, and if reproduction is continued asexually " at each 

 successive stage there is always a chance of some one or more of the 

 various species of germs . . . dying out" (p. 333). Mr. Galton supposes, 

 in sexual reproduction, where two parents contribute germs to the 

 embryo the chance of deficiency of any of the necessary germs is greatly 

 diminished. Darwin's "very different view of the meaning or cause of 

 sexuality " is no doubt that given in Cross and Self Fertilisation i.e., 

 that sexuality is equivalent to changed conditions, that the parents are 

 not representative of different sexes, but of different conditions of life. 



2 "The History of Twins," by F. Galton, Fraser s Magazine, November, 

 1875, republished with additions in the Journal of tJic Anthropological 

 Institute, 1875. ^ r - Galton explains the striking dissimilarity of twins 

 which is sometimes met with by supposing that the offspring in this case 

 divide the available gemmules between them in such a way that each is 

 the complement of the other. Thus, to put the case in an exaggerated 

 way, similar twins would each have half the gemmules A, B, C, . . . Z., 

 etc., whereas, in the case of dissimilar twins, one would have all the 

 gemmules A, B, C, D, . . . M, and the other would have N . . . Z. 



3 We are unable to determine to what paragraphs 5, 6, 7, 8 refer. 



