194 CARNEGIE INSTITUTION OF WASHINGTON. 



The following investigators studied under the auspices of the 

 Department during the year: 



Dr. Paul Bartsch, May 15 to June 20, Andros Island, Bahamas, and Tortugas, Florida. 

 Heredity of characters in hybrids between Bahama and Florida cerions. 



Professor Ulric Dahlgren. Histology of luminous organs of fishes, Provincetown, Massa- 

 chusetts, and Bar Harbor, Maine. 



Professor John H. Gerould. Heredity of characters in Pieridse. 



Professor E. Newton Harvey. Chemistry of animal luminescence. 



Professor WiUiam H. Longlej', Tortugas, June 3 to Sept. 1. Coloration of reef fishes with 

 reference to evolution and environment. 



Alfred G. Mayor, Tortugas, June 1 to July 25. Reactions of ants. 



Professor Asa A. Schaeffer, Tortugas, June 13 to July 25. Marine amoebae. 



Professor A. L. Treadwell, Montego Bay, Jamaica, June 21 to July 25. Eunicidse. 



Accompanied by our chief engineer Mr. John Mills, Doctor Bartsch 

 visited Andros Island, Bahamas, taking with him the small glass- 

 bottomed launch Bull Pup. He was thus enabled to make a large 

 collection of the young snails of the glans type of cerion from the region 

 of Golding Cay, which he hopes to cross with the incanum form of the 

 genus from Florida. The wire cages in which he was conducting these 

 experiments upon Tortugas having been destroyed by the hurricane of 

 September 9, 1919, they were rebuilt by Mr. Mills this summer in 

 such manner that it is hoped they may withstand a hurricane without 

 material damage. Doctor Bartsch was thus enabled to restart his 

 breeding experiments upon Loggerhead Key, Tortugas, which it will 

 take about 10 years to complete. In addition to these studies of 

 cerions. Dr. Bartsch made observations upon the birds of the Bahamas 

 and Florida. 



In 1915, Professor John H. Gerould accompanied our expedition to 

 Porto Rico and made a study of the Pieridse of this island. This 

 research has been continued upon American forms and interesting 

 factors in Mendelian inheritance have been brought to light. 



Professor E. Newton Harvey had a large collection of Cypridina 

 made for him in Japan in order to endeavor to obtain a sufficient 

 amount of luciferase and luciferin for a more definite chemical analysis 

 of these substances. He also studied luminous organisms at Woods 

 Hole and at Bar Harbor during the summer, while Professor Dahlgren 

 gathered material for a study of the histology of luminous organs in 

 fishes. 



Professor William H. Longley continued at Tortugas the study he 

 has pursued for many years upon the selective value of habits and en- 

 vironment in developing the color and patterns of reef fishes. He 

 pursues the direct method of going under water in a diving-hood and 

 observing the fishes in their natural condition. He is provided with 

 a submarine camera, which enables him to obtain photographic records 

 of many occurrences having a bearing upon the problem of his research. 



