I<;KKK<T OKSKASON <>i ii\r<m\<. \n>\ m.vrmm i n.\ m ii.inii.rn. .".7 



In this scries, from :i single season, (here arc III birds \\liirh Jived long enough 

 normally to sock expression of their sexuality. They arose from M series of .'{(I 

 (table 27). They are the result of inbreeding together with "overwork," and (for 

 some of them) late season. All of these factors are seen e|-e\\here. as \\ell as here. 

 to produce weakened germs. In tin* raw. ninr>n r, it imiilti sri-m i 1 i ////// ,ln<l,,/,- 

 mcntal power was bestowed upon tin'* fa in Hi/ xiificiait In /irodnn- /<//////,///// { males, 

 but insufficient In produce fully fertile //m/r.s,- (2) Unit nnlij ihtw fi-mnlr* Unit a 

 from the slromjcr curlier i/crnm r/r /^.s-.xr.s.xa/ of liii/li, full, or <<, //,/</< ,; /,r<,<li'/ii , 

 power. In other words, females only in this family exhibit the function of fertility 

 unreduced; and only those particular females which were obtained from the -tronger 

 earlier eggs of an overworked female parent exhibit an unreduced or but slightly 

 reduced fertility; their sisters from the weaker germs of late in the season show les- 

 fertility or no fertility. This differential of fertility for the sexes was an unexpected 

 though probably a significant result. 



Perhaps if this situation were stated in terms of Professor Whitman's viev 

 fertility, season, and of the relation the sexes bear to each other it would be simply 

 this: The mating of related birds results in weakened offspring; the function of 

 fertility suffers with other functions it too is weakened; the effects of overwork 

 and of lateness of season progressively accentuate this weakness. It would seem 

 from the data of this chapter, that where fertility is much reduced from / 

 sources, 3 fully equipped females though not complete males 4 may be produced; 

 and that this may possibly have a bearing on the author's thesis that "the male 

 goes (and must go) further in development than does the female"; or, again (if 

 the present data were sufficient for a generalization), where developmental energy, 

 from such a reason, is not of normal strength, females may be produced without 

 obvious defect, but males then produced may bear obvious defect. 



It may seem to some that there is here a contradiction of certain aspec: 

 the principle of "reduced fertility in proportion to width of cross" which has been 

 established in earlier chapters; for it was there found that the ctooaee of mo-t 

 widely separated species yield only or almost exclusively males, and that fertility 

 is usually reduced in proportion to the width of crosses. In those cases too the 

 individuals with rudimentary sex-glands were the occasional /emofes, not the males. 

 All is made clear, however, when one distinguishes, as has been done in ( 'hapter III. 

 between the two very different means of reducing the "fertility" of germs. In 

 obtaining males from the "wide crosses," the "strongest" germs of the birds are 

 utilized; and apparently there is here, as in the crossing of varieties, additional 

 "strength" obtained by the mere act of crossing. The reduction of fertility which 

 pertains to such wide crosses rests upon some "incompatibility." or lack of coordi- 

 nation, of the two fused plasms, while the reduced "fertility" which is patent in 

 the data now under consideration rests certainly upon a very different basi- 

 upon "weakness" in fact. Here parents begin by supplying germs at once "weak- 

 ened" by a union with a related (inbred) germ: in addition, too rapid work at 



3 That is, inbreeding and lateness of season associated with overwork. 



4 Recent quantitative studies on sex in pigeons by the editor go very far ton-mi establishing the proportion 

 that males are not only less likely to be. produced, under the extreme conditions referred to here, hut those which do 



:ire. less "masculine" than arc other males. 



'Note that in the family under consideration, 1 male, from the end of the season .had only a single testicle. 



