DEPARTMENT OF EXPERIMENTAL EVOLUTION. 109 



Dr. Banta has spent much time, since Dr. Riddle entered the 

 Army, in revising the proofs of the Whitman volumes. Nearly all of 

 150 pages of tables have been checked and verified by him. 



The experiments with cave forms have been continued. More young 

 have been produced in the cave and the rearing has been more success- 

 ful than in any previous year. During January 1918, Dr. Banta col- 

 lected material in caves near Bloomington, Mitchell, and New Albany, 

 Indiana. The water-level in the caves was low, so that the conditions 

 were favorable for collecting and additional living material of the 

 species desired was obtained and shipped to Cold Spring Harbor. 



Dr. Charles W. Metz reports as follows on his work with the evolu- 

 tion of the germ-plasm. His studies are made with a fruit fly. 



"In view of the fact that I have been engaged in war work during the 

 entire year covered by this report, the research activities in which I was 

 formerly engaged have been greatly curtailed. The essential work of caring 

 for the mutant stocks of Drosophila and the continuation of several of the 

 experiments, however, have been efficiently managed by Dr. Alexander 

 Weinstein in my absence. 



'Although a considerable amount of data has been obtained, there has 

 been no opportunity to work it up, and it is difficult to draw conclusions or 

 make generalizations at this time. Consequently, the following items are 

 intended mainly to show the general nature and trend of the results. 



"Several new mutant characters have been found by Dr. Weinstein in 

 Drosophila virilis, and the linkage relations of these and some of those pre- 

 viously discovered have been determined. These serve to enlarge the linkage 

 groups already identified in this fly. 



'The investigation of incompatibility between mutant (and apparently 

 allelomorphic) characters in D. virilis has been continued. Three characters 

 are involved in this series. 



"Considerable work has been done in the way of further analyzing the 

 group of sex-linked characters in this species and comparing it with the 

 sex-linked group in D. ampelophila. A sufficiently large series of characters 

 is now available in the sex-linked group of virilis to make possible a fairly 

 accurate determination of linkage and cross-over values and a comparison of 

 these values with those in ampelophila. The results continue to indicate 

 a correspondence between the sex-chromosome constitution of the two species, 

 although showing a specific difference in the rate of crossing over. 



"In addition to these features. Dr. Weinstein has been conducting experi- 

 ments on 'coincidence' of crossing over in D. virilis, a line of work not pre- 

 viously attempted with this material." 



About three years ago Dr. E. C. MacDowell began experimentation 

 on the effect of ingestion of alcohol on rats to test the view that alcohol 

 can permanently affect the germ-plasm. During Dr. MacDowell's 

 absence in France the work has been carried on by his assistant, 

 Miss Vicari. The following report is submitted: 



"Relative intelligence of rats of alcoholic and non-alcoholic parentage. — The 

 alcoholization of the albino rats has been continued in the first generation 

 and carried on to the second. The main work of the year has been testing 

 the learning capacity of: (1) the offspring of alcoholic grandparents; (2) the 



