DEPARTMENT OF GENETICS. 115 



tional material and to serve as checks upon various conclusions justifies the 

 relatively small amount of labor involved in its maintenance. In these lines 

 various mutations have arisen. The physiologically different strains of line 

 757, whose histories are set forth in Carnegie Institution of Washington 

 Publication No. 305, and the sex-intergrade (physiologically and morphologi- 

 cally distinct) strains of Simocephalus spinosus and Daphnia longispina, have 

 been previously mentioned in these reports. 



Two new mutations have arisen during the past year, both involving the 

 head form in Daphnia longispina. The first of these mutations is a marked 

 indentation of the front of the head serving to lengthen the anterior margin of 

 the beak and imparting to these "excavate head" animals a somewhat gro- 

 tesque appearance. The second mutation is a shortening of the posterior 

 beak margin, and while less striking in appearance than the other, nevertheless 

 seems to be a good character. Work is being done on the inheritance of these 

 new characters. 



A point of interest with reference to excavated head is the undoubted re- 

 currence of the mutation. Occurring first in September 1921, it reappeared 

 in another strain in the following February, in a third strain in June, and in a 

 fourth strain in August. It is worth noting that the occurrences of this muta- 

 tion are in strains originating from three of our original intergrade strains, 

 which, though having a common origin, had been separate for 104 generations 

 covering a period of over four years. 



Eyelessness in Cladocera. 



To the three cases of eyelessness in Cladocera mentioned a 3^ear ago, Dr. 

 Banta has been able to add 10 additional cases. As in the cases reported 

 before, the optic ganglia were partially or completely aborted, and in some 

 cases the stem-like structures, which possibly represented aborted primordia 

 of the eye and adjacent structures, were present on the front of the head in 

 the young eyeless individuals. The sporadic occurrence of these eyeless in- 

 dividuals (7 were in a single bottle), their occurrence in some cases in bottles 

 in which other abnormal individuals arose, and the lack of inheritance of the 

 character, indicate that these are merely somatic alterations due to environ- 

 mental factors. However, since eyelessness is a chracteristic of many 

 cave animals, it is believed that any occurrence of such a trait should be 

 carefully followed up. 



Studies on the Vascular Anatomy of Normal and Teratological Seedlings of 



Phaseolus vulgaris. 



Further studies on the vascular anatomy of normal and teratological seed- 

 lings of Phaseolus have been carried out by J. A. Harris, E. W. Sinnott, J. Y. 

 Pennypacker, and G. B. Durham. These data have heretofore been treated 

 from the purely anatomical side, but are to be used in connection with studies 

 on natural selection, for which the experimental records are already availa- 

 ble. 



STUDIES ON HUMAN GENETICS. 

 Heredity in Aristogenic Families. 



Dr. H. J. Banker has spent much time in collecting scholarship records in 

 coeducational schools, with the aim of studying inheritance of special scholar- 

 ship. An attempt was then made to analyze this material statistically. The 



