250 THE WONDERS OF INSTINCT 



appear : the egg, as it descends from its ovarian tube, has 

 no determined sex. It is perhaps during the few hours 

 of its rapid development at the base of its ovarian sheath, 

 it is perhaps on its passage through the oviduct that it 

 receives, at the mother's pleasure, the final impress that 

 will produce, to match the cradle which it has to fill, 

 either a female or a male. 



Permutations of Sex 



Thereupon the following question presents itself. Let 

 us admit that, when the normal conditions remain, a 

 laying would have yielded m females and n males. Then, 

 if my conclusions are correct, it must be in the mother's 

 power, when the conditions are different, to take from 

 the m group and increase the n group to the same extent ; 

 it must be possible for her laying to be represented as 

 m i, m 2, m 3, etc. females and by n + i, 

 n -f- 2, n -f 3, etc. males, the sum of m -j- n remaining 

 constant, but one of the sexes being partly permuted into 

 the other. The ultimate conclusion even cannot be dis- 

 regarded: we must admit a set of eggs represented by 

 m m, or zero, females and of n -f- m males, one of the 

 sexes being completely replaced by the other. Con- 

 versely, it must be possible for the feminine series to be 

 augmented from the masculine series to the extent of 

 absorbing it entirely. It was to solve this question and 

 some others connected with it that I undertook, for the 

 second time, to rear the Three-horned Osmia in my study. 



The problem on this occasion is a more delicate one; 



