240 REPORTS ON INVESTIGATIONS AND PROJECTS. 



separated parts of the country, as from the Pacific Coast and New England, 

 with a view of studying the inheritance in such crosses. 



Mr. C. C. Little, a research student, has completed an important investiga- 

 tion of color-inheritance in mice. A preliminary paper on this work was 

 published in September 1909 (see Bibliography, p. 48) ; a fuller paper is 

 partly in manuscript. He has been able to make a more complete analysis 

 of color-inheritance in these much-studied animals than has heretofore been 

 made and to clear up several puzzling cases by use of the Mendelian hypoth- 

 esis. Mr. Little is also beginning a systematic study of inheritance in pigeons 

 and in dogs. 



Mr. John Detlefsen, Austin Teaching Fellow in Zoology in Harvard Uni- 

 versity, is assisting in three distinct lines of work. Ovarian transplantation 

 in frogs has given us, so far, only negative results; injection of various solu- 

 tions into the reproductive glands of rats has likewise given negative re- 

 sults ; the study of hybrids between Cavia aperea and the guinea-pig is giving 

 results of interest. The curious sterility (in the male sex only) of those 

 hybrids has been described in previous reports. At last a partially fertile 

 male hybrid has been obtained, a one-eighth blood aperea, seven-eighths blood 

 guinea-pig. A detailed study is being made of the size, color, proportions, 

 and rate of growth of the various sorts of hybrids obtained, which range all 

 the way from one-half blood to one thirty-second blood aperea. No publi- 

 cation has yet been made upon this investigation, though it has been in prog- 

 ress for some years and the results already obtained are considered impor- 

 tant. The next year's work upon this problem should be productive. We 

 are planning to carry it out on a considerable scale. 



Mr. E. C. MacDowell, a graduate student, has aided in studying size- 

 inheritance in rabbits. This is apparently non-Mendelian, but may prove to 

 be a complex Mendelian case. Large numbers of animals carefully studied 

 from birth to full maturity are needed to solve this problem. Such data are 

 being secured, and Mr. MacDowell is proving to be a careful and critical 

 student of them. 



Selection for size in guinea-pigs (see last report) has been continued with 

 the assistance of Mr. Detlefsen and Mr. J. W. Chapman, a graduate student 

 in zoology. Professor Castle is studying some problems in color-inheritance 

 in rabbits in connection with Dr. P. B. Hadley, of the Rhode Island Agri- 

 cultural Experimental Station. 



The Harvard authorities have greatly increased the facilities for work by 

 building new cages, a pigeon-house, and a yard for dogs. They are now 

 adding a new section to the basement breeding-rooms for the further exten- 

 sion of the experiments with rabbits and guinea-pigs. Four papers have 

 been published since the last report. (See Bibliography, pp. 47, 48.) 



