66 REPORTS O^ INVESTIGATIONS AND PROJECTS. 



to the rate of growth, density of distribution, methods of propagation, and 

 morphology in his own laboratories at the Alabama Polytechnic Institute at 

 Auburn, Alabama, 



Dr. T. Whittelsey, of Northwestern University, who also gave a year of 

 service to a study of the chemistry of the products, has continued his work 

 and will join with Professor Lloyd in preparing a manuscript dealing with 

 the entire matter, which will be presented for publication shortly. 



The Influence of Environmental Factors upon Beetles in Pure Lines and in 

 Hybridization (by Prof. W. L. Tower) : 

 The investigations of Prof. W. L. Tower, of the University of Chicago, 

 upon the reaction of the chrysomelid beetles to environmental or climatic 

 factors, have now been carried through the second year at the Desert Labora- 

 tory, and the following communication from him describes the progress 

 attained : 



That portion of my work which has been carried on at the Desert Labora- 

 tory during 1909 consisted in the continuation of the work of 1908, its 

 expansion, and the addition of much new material. Tucson affords a typical 

 desert environment, and all of the experiments placed at Tucson, thus far, 

 are arranged to give exact data concerning the action of the physical portion 

 of a desert habitat upon the animal organism. 



Three distinct sets of experiments are being conducted at Tucson, as a 

 part of a larger series which is planned to give precise information upon 

 three vital processes in the evolution of organisms, viz: (i) The action of the 

 physical environment upon species and races migrating into or suddenly 

 introduced into new environmental complexes; (2) the action upon and the 

 relation of the physical environment to the processes of variation, heredity, 

 elimination, and conservation; (3) the relation of the physical environment 

 to the interaction between two or more freely interbreeding species, when 

 introduced or coming into contact in the midst of different environmental 

 complexes. 



In all of the experiments directed toward the solution of these problems 

 cages of fine pearl-wire cloth, 22 meshes to the inch, have been used, with 

 strong wire bottoms which completely prohibit all insectivorous enemies. 

 The organisms employed are free from parasitic attacks and from the rav- 

 ages of disease, so that the results coming from each culture represent the 

 direct interaction of the organisms and the physical environment, the selective 

 effect of predaceous organisms being totally eliminated. The results are 

 further guarded by using only stocks whose traits are known for many 

 generations, and these same stocks are further subjected to similar experi- 

 ments in other complexes, so that the results can not be due to latencies 

 or orthogenetic tendencies becoming actuated under the conditions of the 

 experiment. 



The plant for this investigation at Tucson now consists of 34 large cages 

 and a large ware inclosure for pedigree cages, with the minor apparatus 

 needed. Three locations at Tucson are utilized, which give different com- 

 plexes in close proximity, yet with sufficient contrasts to make experimenta- 



