REPORT OF EXECUTIVE COMMITTEE. 1 39 



quitoes actually under study amounts to 94, of which the early 

 stages of 65 have been observed and collected. The plan followed 

 during 1903, of employing local observers, was during 1904 done 

 away with to a large extent, only two such observers, one in Mon- 

 tana and the other on the southwest coast of Mexico, being em- 

 ployed. General collecting trips were made by two assistants, fol- 

 lowing the line of demarcation of the upper and lower austral zones 

 from south Texas to Virginia, in the course of which many facts of 

 importance were gathered regarding the northward distribution of 

 the yellow-fever mosquito. Another trip was taken with a similar 

 purpose into south Mexico, where the influence of altitude upon the 

 distribution of this important species was carefully studied. The 

 preparation of the illustrations for the monograph has been begun, 

 and 37 species of adults and 23 species of larvae have been drawn in 

 admirable style. At the time of writing other drawings were under 

 way, including a series indicating the anatomical details of the early 

 stages. An enormous number of individuals of the different species 

 have been received, and some very curious results have been obtained, 

 indicating the presence in some cases of two or more distinct species 

 indistinguishable by study of the adults alone, surprising larval 

 differences indicating the fact. 



C. E. McClung, Kansas University, Lawrence, Kans. Grant No. 16. 

 For making a comparative study of the spermatogenesis of insects, 

 etc. (For first report see Year Book No. 2, p. xliii.) $500. 



Abstract of Report. — The second year's work by the holder of this 

 grant has again been largely that of preparation of material for 

 study. There is now on hand an extensive series of specimens which 

 will make possible a comparative study of almost a hundred species 

 of Orthoptera. A part of this material has been subjected to the 

 action of radium and chemicals in the hope of producing some alter- 

 ation of the chromosomes in division that would throw some light 

 upon normal processes. No forms outside of the insects, in which 

 hybrids could be obtained, exhibited satisfactory chromosomes, and 

 so far it has not been found possible to secure the desired hybridiza- 

 tion of insects, so that this most important part of the investigation 

 will have to be postponed. The present work will be devoted to the 

 study of two closely related species of one genus in which there are 

 strongly marked chromosomes in the hope of determining some rela- 

 tion between the individual chromosomes and body characters. In 

 connection with this two closel)' related genera will receive a similar 



