The Mother Decides the Sex 



mcnts are {cw in number and of all shapes 

 and sizes. There are long and short ones, 

 spacious ones and narrow. Short of ex- 

 patriating herself, a Spartan course, she has 

 to use them all, from first to last, for she has 

 no choice. Guided by these considerations, I 

 embarked on the experiments which I will now 

 describe. 



I have said how my study, on two separate 

 occasions, became a populous hive, in which 

 the Three-horned Osmia built her nests in 

 the various apparatus which I had prepared 

 for her. Among these apparatus, tubes, 

 either of glass or reed, predominated. There 

 were tubes of all lengths and widths. In the 

 long tubes, entire or almost entire layings, 

 with a series of females followed by a series 

 of males, were deposited. As I have already 

 referred to this result, I will not discuss It 

 again. The short tubes were sufficiently 

 varied in length to lodge one or other por- 

 tion of the total laying. Basing my calcula- 

 tions on the respective lengths of the cocoons 

 of the two sexes, on the thickness of the par- 

 titions and the final lid, I shortened some of 

 these to the exact dimensions required for two 

 cocoons only, of different sexes. 



133 



