y8 REPORTS ON INVESTIGATIONS AND PROJECTS. 



Island for this experiment, as it seemed to offer ideal conditions and as 

 brown rats were known to inhabit it. An attempt was made to kill off the 

 brown rats, and several pairs of white rats were then set free June 21, 1910. 



The conclusions of Dr. C. C. Guthrie, that germ-cells of one race of poul- 

 try introduced into another race produced offspring with some of the char- 

 acters of the foster-mother, was thoroughly tested by me, using pedigreed 

 stock, and overthrown. There is at present no evidence that, in poultry, 

 transplanted germ cells survive, much less that the "foster mother" modifies 

 the inherent inheritable characters of the germ plasm. 



On the other hand, the germ cells do receive nutritive materials from the 

 maternal body and the details and limitations of this process are of great 

 importance. Dr. Oscar Riddle, of the University of Chicago, spent some 

 time at this Station during the year investigating this topic. Particularly 

 he studied the permeability of the envelopes of the animal germ cell (fowl) 

 to foreign bodies — especially to natural and artificial coloring matters. Posi- 

 tive results were obtained with nine such substances, and negative results 

 with about forty others. He also studied the oxidizing and reducing proper- 

 ties of germinal elements and their surrounding tissues as these can be meas- 

 ured in the fowl by means of reducible and reoxidizable color-compounds. 

 The investigation of both these subjects is still incomplete. 



THE RELATIONS OF CHARACTERISTICS. 



By means of extensive statistical studies Dr. Harris has determined that 

 in Staphylea there is a real selective elimination of the fruit with fewer and 

 more variable ovules and of those that are asymmetrical or have an odd 

 number of ovules to a compartment of the ovary. To studies in elimination 

 which stop at mere statement of the statistical fact there will always be the 

 unsatisfied inquiry as to the mechanism of this elimination. 



A case (land snails of the Bahama Islands) that has lately been cited as 

 evidence against mutation was examined by me at New Providence and facts 

 found that support the interpretation of their mutational origin or at least 

 do not warrant the conclusion that the various forms can have arisen only 

 by "selection." 



STAFF. 



Dr. G. H. Shull spent a larger part of the year than usual (all except 

 January to April) on the Burbank work at Santa Rosa, and he will continue 

 there until next spring. The necessary but difiicult work of supervising the 

 planting and hand-pollinating of Dr. Shull's cultures was done in a satisfac- 

 tory manner by Mr. R. C. Rose, now of the New Hampshire Experiment 

 Station, who was resident from June i to September 10. Dr. J. A. Harris 

 spent some months in England and Germany during the winter, carrying on 

 his computations and writing up results there. Dr. Banta visited Mayfield's 

 Cave, Indiana, during a part of May in order to get cave animals for his 

 studies at Cold Spring Harbor. 



