THE OSMLE 263 



females appear. The smallness of the space has almost 

 done away with the stronger sex. This result is demon- 

 strated by the sixty-eight Snail-shells colonized. But, of 

 this total number, I must use only those series which re- 

 ceived an entire laying and w T ere occupied by the same 

 Osmia from the beginning to the end of the egg-season. 

 Here are a few examples, taken from among the most 

 conclusive. 



From the 6th of May, when she started operations, 

 to the 25th of May, the date at which her laying ceased, 

 one Osmia occupied seven Snail-shells in succession. 

 Her family consists of fourteen cocoons, a number very 

 near the average ; and, of these fourteen cocoons, twelve 

 belong to males and only two to females. 



Another, between the 9th and 27th of May, stocked 

 six Snail-shells with a family of thirteen, including ten 

 males and three females. 



A third, between the 2nd and 29th of May colonized 

 eleven Snail-shells, a prodigious task. This industrious 

 one was also exceedingly prolific. She supplied me with 

 a family of twenty-six, the largest which I have ever ob- 

 tained from one Osmia. Well, this abnormal progeny 

 consisted of twenty-five males and one female. 



There is no need to go on, after this magnificent exam- 

 ple, especially as the other series would all, without ex- 

 ception, give us the same result. Two facts are immedi- 

 ately obvious : the Osmia is able to reverse the order of 

 her laying and to start with a more or less long series of 

 males before producing any females. There is some- 

 thing better still ; and this is the proposition which I was 



