spermatogenesis of the Mongoose, etc. 175 



judged from his illustrations, seems far from conclusive. In fact, the 

 hypothetical so-called X-element ("accessory body") in the ovary lacks 

 much of being similar in structure and behavior to the undoubted X-element 

 in (Edipus (described and figured in the same paper) and the male Gryllus. 

 Moreover, Gutherz (1910) has shown that the two X-chromosomes, char- 

 acteristic of the female, are both present in the metaphase plates of the 

 oogonia, in addition to the outlying "accessory body." As is now estab- 

 lished beyond any doubt the accessory, for example, of the male germ-cells 

 passes into all females. Its homologue is present in both males and females ; 

 but the additional male accessor>% at any rate, would seem to be able again 

 to comport itself during the growth stage of the maturing oocyte as it 

 originally behaved in the growing spermatocyte; and similarly with respect 

 to its female homologue, since that in the male, coming originally also from 

 the egg, behaves again in typical "accessory" fashion. It seems fairly 

 well established that the female homologues of the male accessory do not 

 behave in the growing oocytes as does the X-element in the spermatocyte. 

 As indicated by observation on the cat, the reverse of the usual relation- 

 ship here obtains: the oocytes are probably dimorphic with respect to an 

 accessory; the spermatocytes apparently monomorphic. Here, then, as in 

 certain sea-urchins, the female is apparently digametic, the male apparently 

 homogametic. Further investigations must establish the fact whether the 

 same reverse condition obtains with respect to an X-element in the case 

 of the remaining four mammals of the first group. 



Male and female sex (together with secondary sexual characters) appear 

 to be hereditary in a manner similar to other organic characters, and may 

 be regarded as a pair of "unit characters." Since the femaleness is associ- 

 ated with, or determined by, the presence of X-elements, the female (con- 

 taining a pair of homologous X-elements) is presumably homozygous,^ the 

 male heterozygous for sex; or, in accordance with a more recent termin- 

 ology, the female represents a duplex (but apparently recessive like a nuUi- 

 plex) condition, the male a simplex (dominant) condition. Maleness is 

 accordingly characterized by the absence, femaleness by the presence of a 

 "determiner" (presumably an inhibitor), the X-element. The former is 

 the negative or minus (lacks accessory, contributed to female at fertili- 

 zation), the latter the positive or plus, condition. Sex inheritance con- 

 forms thus to the Mendelian scheme, in which maleness represents the DR 

 and femaleness the RR condition; or, stated in terms of the presence (-f ) 



and absence ( — ) of an inhibiting accessory, or X-element, maleness is -^ , 



and femaleness the -f -j- condition. Femaleness may therefore be plus or 

 positive in an inhibiting sense ; a germinal plus condition prevailing in the 

 female, inhibiting the appearance of a positive somatic condition or male sex. 

 This modified Mendelian interpretation is suggested in part by an 

 analogy with conditions in crosses between horned and hornless cattle, 

 where the positive character (horns) is recessive to the negative or hornless 



I That i3, in the group where the male germ-cells contain an X-element. 



