DEPARTMENT OF GENETICS. 103 



completely absent. This condition may or may not be accompanied by abnor- 

 malities of the mouth and jaw already referred to. When the mouth is normal 

 and one or both eyes abnormal, the mice may live for 5 or 6 weeks. Such 

 individuals are, however, always undersized, highly nervous, and weak. 

 None of them has attained breeding age. The effect of this modification is, 

 then, always lethal, although the lethal action may be in some cases delayed 

 for a considerable period. 



" (3) Foot and leg abnormalities. — These involve a reduction of digits, syn- 

 dactylism, and other abnormalities of any or all of the feet and legs. This 

 abnormality in all probability bears some relation to the eye-lesion abnor- 

 mality, although the genetics have not been clearly worked out as yet. 



" (4) Hair abnormality. — This involves a shortening of the hair on one or 

 both flanks. In pigmented mice this produces a lighter degree of pigmentation 

 in the regions where the hair is shorter, thus producing a "saddle" effect. 

 This abnormality has not yet been worked out in relation to those already 

 described, but it is clearly distinct and is extremely striking in appearance. 

 Its identity as a structural character has been determined by its appearance 

 on an albino. 



"(5) Lesions involving the entire cranium. — These occurred in the same 

 family as that giving the first described type of hemorrhagic eye abnormality 

 in some 8 or 9 mice which were born dead with partial or total absence of the 

 cranium. These acraniate forms are very striking and are unlike any other 

 abnormalities hitherto described in mice. 



" (6) Minor abnormalities of the eye involving breaks in the ring of iris 

 'pigment to greater or lesser extent. These have occurred in only a few cases and, 

 as it happens, the mice have not survived. 



" (7) Spinal lesion. — This has occurred in one animal, resulting in death a 

 short time after birth. The lesion was in the sacral region, and superficially 

 resembled spina bifida." 



In order to determine whether or not there is a direct effect of X-rays upon 

 the treated animals themselves, Miss Margaret Schneider and Mr. L. H. 

 Snyder are sectioning a series of eyes and gonads of animals which received 

 the same dose as did those used in the original X-ray experiment. 



MODIFIABILITY OF THE GERM-PLASM BY ALCOHOL. 



This experiment, which has been continued for 6 or 7 years, may now be 

 considered practically completed. Though with the use of rats no such 

 striking results were obtained as reported by Stockard for guinea-pigs, never- 

 theless a clear effect of alcohol in reducing the capacity for learning in the 

 treated generation was found; and this effect persisted to the next generation, 

 even if that generation was not subjected to further alcohol. 



It remained to learn if there were any slight morphological effects of the 

 alcohols, and, if so, any persistence of those effects to the next generation. 

 To this end the skull and the bones of the appendages were saved for measure- 

 ment. By an accident many rat skulls of the parental and first filial genera- 

 tions were destroyed. However, 472 skulls altogether have been measured 

 in four dimensions: total length, width, height, and length of nasal bones. 



When this total is subdivided according to the generation and sex, the 

 numbers are too small to afford a basis for any conclusion as to the relative 

 size of tests and controls. The work was done under Dr. MacDowelPs direc- 

 tion by the Misses Vicari and Hubbard. 



