DEPARTMENT OF GENETICS. 113 



in doses that varied from 12 seconds to 360 seconds in exposure time. 

 A 2.5-inch spark-gap was used, 10 milHamperes, and 12-inch distance. 

 129 mice were X-rayed. Several of the mice treated with the smaller 

 doses mated and produced apparently normal young in the first 

 generation. These were again inbred, and two young mice were found 

 with apparently very abnormal eye conditions. These animals were 

 found in the first and second litters of a single Fi female. The de- 

 velopmental condition of the eye is apparently an index of disturbance 

 in mammalian development in general, and the presence of these eye 

 disturbances, occurring in a strain of animals which otherwise rarely 

 show such malformations, is an interesting observation in itself; 

 it is strongly suggestive of the possibility of altering the genetic con- 

 stitution of these animals in still further ways. Recently some of the 

 apparently normal Fi animals were autopsied, and certain of the skulls 

 have shown a peculiarly abnormally rounded dorsal convexity, asso- 

 ciated with a slight asymmetry of the entire skull. Detailed his- 

 tological study of these abnormal structures is being made at the time 

 of writing. Further experiments are planned for the treatment of 

 successive generations of mice with small doses of X-rays. The treat- 

 ments were made by Dr. Bagg at the Memorial Hospital, New York 

 City, while the actual breeding experiments and the detailed care of 

 the animals were carried on at Cold Spring Harbor. 



MODIFIABILITY OF THE GeRM-PlaSM BY AlCOHOL. 



Under this heading, or a similar one, there has been given in the 

 Year Book since 1914, an account of an experiment on the effect upon 

 the descendants of alcoholization of the ascendants. The account of 

 the results obtained this year are accordinglyplaced here again. Mean- 

 while, it must be admitted that a large part of the clear results obtained 

 are probably due to a selective elimination of certain genotypes through 

 a direct physiological effect of alcoholization upon the mother, although 

 it is still probable that some modification of germinal material has 

 taken place. Dr. MacDowell reports: 



"Behavior in multiple-choice apparatus: In the Year Book, 1920, pages 

 118-122, appeared a description of the operation of this apparatus. The 

 summarization of the data from the children of treated rats can now be 

 reported. The general features of the curves of correct and wrong choices 

 for this generation are very like those formerly presented for the generation 

 of the grandparents. 



"The data for the offspring of treated rats (81 tests and 80 controls) came 

 from two series of experiments: a first series in which the parents were 

 given relatively light doses of alcohol, and a second series in which the parents 

 were given alcohol fumes each day until the state of complete stupor was 

 produced. All interpretation is dependent upon the significance attached to 

 the performance in the preliminary trials, which differed from the regular 

 trials in that the rats were fed in the first compartment chosen by them in 

 those trials. Is the difference between the tests and controls (manifest in 



