124 CARNEGIE INSTITUTION OF WASHINGTON. 



REPORTS ON INVESTIGATIONS IN PROGRESS. 



THE GERM-PLASM AND ITS MODIFICATION. 

 COMPARATIVE STUDY OF THE CHROMOSOME GROUPS IN DIPTERA. 



Dr. IMetz has resumed his studies on spermatogenesis in Drosophila 

 and other Diptera. Studies on D. virilis and on two species of Asilidse 

 were almost completed by September. 



COMPARATIVE GENETICAL STUDIES OF DROSOPHILA. 



During the past year, Dr. Weinstein, while caring for the mutant 

 stocks, analyzed the relationship between certain of the mutant char- 

 acters in Drosophila virilis that had not previously been fully analyzed. 

 Since Dr. Metz has taken up the work, considerable progress has been 

 made in obtaining new mutant characters in Drosophila virilis, D. 

 obscura, and D. willistoni and in analyzing their mode of inheritance 

 in accordance with the plan outlined previously for ascertaining the 

 chromosomal and genetical relationships between different species of 

 Drosophila. He states that 23 new mutant characters were found in 

 the five months, March to July inclusive. 



MODIFIABILITY OF THE GERM-PLASM BY ALCOHOL. 



The effect of alcohol on the capacity for forming habits (as a test of 

 intelligence) and the recurrence of the effects in later generations of 

 the alcoholized ancestors have been the subjects of Dr. E. C Mac- 

 Dowell's research for several years. This year there is no new experi- 

 mental work to report. Dr. MacDoweli reports as follows : 



"During four years data were continuously being collected; very little time 

 for their summarization, or even primary tabulation, was availalDle. It has 

 seemed important to complete the tabulation and the analysis of these exten- 

 sive masses of data and publish the results before again becoming too deeply 

 involved in the carrying on of new experiments. Besides their significance 

 for the primary question as to the modifiabihty of the germ-plasm, these data 

 will provide evidence upon such problems as growth, the relative signifi- 

 cance of different criteria for judging animal behavior, and the immediate 

 effects of alcohol upon mental and physical traits. In view of the large 

 amount of time and money that has been spent upon the collection of these 

 data, the greatest possible use should be made of them. The hazards of 

 deciding mental problems in terms of numbers are great enough in them- 

 selves, without leaving any suspicion that the conclusions may depend upon 

 the special statistical treatment employed. To guard against this danger, 

 it will be necessary to treat the data in various ways, using different combi- 

 nations and methods of averaging. The intensive study of the individual 

 record-sheets showing the track followed in each trail of every rat will serve 

 as an important check upon the statistical results. The conclusions reached 

 from the study of the relative value of the various criteria employed will 

 have a close bearing upon the general conclusion. Three different experi- 

 mental methods have been employed, and the degree of success in each one is 

 measurable in various ways. When Miss Vicari left this laboratory to enter 

 the University of Minnesota under Professor J. B. Johnston, she took with 



