BREEDING EXPERIMENTS WITH BREMUS QUEENS. 327 



The methods employed by Lindhard ('12), differ in several re- 

 spects from those of Hoffer ('82) and Sladen ('12). Lindhard 

 (PP- 337' 338) used nest-boxes which were constructed as 

 follows: Each nest-box consisted of two compartments of about 

 20x20x20 cm. each, one of which may be called the front com- 

 partment, or No. i, and the other the rear compartment, or No. 

 2. On one side, compartment No. I had a glass pane to admit 

 light. At the base, this compartment was provided with two 

 flight-holes, a and b; a, communicating with the outside world, 

 and b, with compartment No. 2. Both flight-holes could be 

 opened and closed. 



After lining compartment No. 2 with a layer of sod, about 5 cm. 

 thick, Lindhard (p. 337) filled the interior with dry grass and the 

 like. In some cases (cf. p. 341), a small paste-board box, filled 

 with moss, and provided with a glass cover, was placed in the 

 compartment instead of sod, and was surrounded with loose 

 earth. With this arrangement, it was possible to place food in 

 compartment No. i without disturbing the queen while she was 

 engaged with her nest in the other compartment, and to keep the 

 nest at a more uniform temperature. 



As food, Lindhard (p. 337) provided a 50 per cent sugar solu- 

 tion and flowers, preferably those from which bumblebees were 

 then obtaining pollen out in the open. After the queen had begun 

 nest-building, the flight-hole was opened so that she could gather 

 pollen from large bouquets which were put in the room in which 

 the box was kept. As soon as the first worker emerged, the colony 

 was placed out of doors where further development proceeded 

 under normal conditions. In subsequent experiments, the queens 

 were permitted to forage in the open shortly after they had begun 

 nest-building. This method promised equally satisfactory results 

 at the time Lindhard ('12) reported his work. 



In his breeding experiments with Bremus auricomus, Prison 

 ('18) confined two queens in one box, but, unlike Sladen (p. 131), 

 found that they did not kill each other. As nesting material, 

 Prison ('18, p. 44) supplied an old field-mouse nest in which he 

 placed a honey-moistened lump of pollen. In addition to this, 

 the queens were given a mixture of honey, rye-flour, and water. 



The methods which were used in my own experiments, may be 



