372 THE GERM-PLASM 



in the germ-plasm of the father, a favourable reducing division 

 is necessary if the son is to remain free from the disease. We 

 can, moreover, even account for those cases in which several 

 female memljers of a ha?morrhagic family in which the fathers 

 were healthy, bear sons all of whom suffer from the disease. 

 For the ' male ' halves of the double-determinants in almost all 

 the ids might have undergone a pathological change in the 

 germ-plasm of the mothers, without producing any apparent 

 result in them ; in the sons, on the other hand, this would 

 lead to the development of the disease, unless an unusually 

 favourable reducing division had counteracted the marked pre- 

 ponderance of the morbid determinants. Hsmophilia, which 

 remains latent in the mother, is just as liable to be transmitted 

 by the mother to her male descendants as is any other mascu- 

 line characteristic of the grandfather, such as the colour of his 

 beard, or the quality of voice. 



It seems to me that we cannot overlook the indication afforded 

 by this agreement between tlie mode of transmission of ordinary 

 sexual characters and of hicmophilia that all, or nearly all. the 

 deter)ninants in the liioitaii ger)n are double, half being •male'' 

 and half ' female," so that a determinant for any particular part 

 may cause the development of the male or female type of the 

 corresponding character. 



The facts which Prosper Lucas * brought forward, and illus- 

 trated by numerous examples, concerning the occasional trans- 

 mission of new characters to one se.x only, — even when they 

 have nothing to do with secondary sexual characters in the strict 

 sense, — may be understood by this assumption of a wide distri- 

 bution of double-determinants in the germ. The modification 

 affects only the ' male ' or the * female ' halves of these deter- 

 minants of the germ-plasm in such instances. This is true 

 as regards the disease we have just considered, inasmuch 

 as it must have made its first appearance at some time or 

 other, — as well as in numerous instances of colour-blindness, of 

 the po.ssession of supernumerary fingers, of the absence of certain 

 fingers or of segments of fingers, and so on. Even the peculiar 

 nature of the epidermis in the well-known case of Lambert, the 

 ' porcupine-man,' was only transmitted to the male descendants. 



* ' Traite philosophique et physiologique de I'heredite naturelie,' Tom. 

 II., Paris, 1850, p. 137. 



