EXPERIMENTAL BIOLOGY 



589 



Meal-worms constitute the most useful general food. These larvae are 

 placed in small, oval, porcelain sugar-bowls which because of their con- 

 cave sides, prevent escape. For different animals it is necessary to pro- 

 vide scraped meat, fresh ant pupae, earthworms, snails, flies, kitchen 

 scraps, chopped fruit and vegetables, as well as any small animals avail- 

 able. Careful attention is given to cleaning the cages. The water 

 basins are emptied by siphons and then sponged. The plants in pots 

 and tufts of moss and turf are changed, stones and wood scoured with 

 hot water and the upper layer of sand or earth renewed. Smaller 

 vivaria are employed for special experiments. In these a double cover 



Fig. 6. Interior of the Glass House for Low Te.mperatubes. 



of gauze provides an air space to ensure the circulation of air. The 

 nests of social insects, like bumble bees and burrowing wasps, are trans- 

 ferred from their natural locations in the late evening when all of the 

 family are at home. The insectaria are then placed in moss-covered 

 ditches, or else buried in the earth, and in a few days the insects 

 become quite contented. 



In order to mitigate the conditions of confinement which unfavor- 

 ably affect certain animals there are four large and many small out- 

 door terrari a (Fig. 3). 



There is a separate house (Fig. 4), bowed around the north side of 

 the grounds, for heredity researches upon the higher vertebrates. Each 

 of the sixteen cages has an outwardly-sloping cement floor, wire screen 

 ventilators, heating pipes and electric lights, and opens into a garden 



