BIOLOGY, EXPERIMENTAL — DAVENPORT. 89 



INVESTIGATIONS ON INSECTS. 



Insects are probably to-day the most rapidly evolving of all organ- 

 isms. This conclusion is based on their great variability. The num- 

 ber of described species is reckoned at hundreds of thousands, about 

 equal to the number of all other animals put together. The static 

 study of their variability has long been carried on, but relatively 

 little breeding of them has been done because of the technical 

 difficulties. The greatest difficulties are uncertainty of pairing in 

 captivity and the infertility of many crosses. To circumvent these 

 difficulties it will be necessary to devise special methods of housing 

 and caging them. We are planning an insectary. Smaller cages 

 for individual experiments are being constantly devised. Each 

 experiment with a new kind of insect requires a careful study of 

 conditions of food, moisture, temperature, light, and air. Changing 

 food of the insects and keeping the cages clean take much time 

 and limit the number of experiments that one man can undertake ; 

 consequently results from insects come rather slowly at first. For- 

 tunately they breed rapidly and produce a great number of offspring ; 

 so when the technical difficulties are overcome they should prove 

 the best of material for our studies. 



Mr. F. E. Lutz has attacked the difficulties of breeding insects with 

 energy and success, and, barring accidents, should gain important 

 results by another season. His report will be found on page 100. 



Mr. Roswell Hill Johnson, who began work here in August, is 

 working on lady birds (Coccinellidtz) a family of beetles which con- 

 tains thousands of species, many of uncertain systematic status. 

 They feed on plant-lice (aphids). His experiments have led him 

 to undertake the systematic cultivation of aphids by rearing their 

 food plants, and even to a study of their diseases. Mr. Johnson 

 reports on page 102. 



Prof. W. J. Moenkhaus, of Indiana University, associate of the 

 station, worked during two months of the summer at the station 

 upon the question of sex-inheritance, using some small, rapidly breed- 

 ing flies for the purpose. He reports on his work at page 102. 



Prof. H. E. Crampton, Columbia University, an associate, has 

 been working on selection in the Saturnid moths. He has made use 

 of the facilities of both the biological laboratory and the station for 

 his breeding work. 



Mr. W. L,. Tower, University of Chicago, an associate, has con- 

 tinued his investigations on the evolution of the Colorado potato 



