GENE AND CHROMOSOME MUTATIONS 241 



Edromelie. ^Ahstnce of tibia from hind legs. Perhaps recessive with 

 normal overlaps. Rabaud and Hovelacque, 1923, Bull. biol. France et 

 Belgiqiie 57: 401-468. 



Eyelids open at birth. — Often not symmetrical on two sides. Perhaps 

 recessive with normal overlaps. Loeffler, 1932, Z. ind. Abst.- u. Vereb. 

 61 : 409-446. 



Hcaddot. — White dot on head. Irregular recessive probably distinct 

 from piebald. Little, 1926, Anat. Rec. 34: 171. Keeler, 1935, Proc. Nat. 

 Acad. Sc. 21:379-383. 



Hound-ear. — Varies from slight reduction of pinna to absence of outer 

 ear. Recessive with numerous normal overlaps. Feldman, 1932, Proc. 

 Sixth Int. Cong. Genet. 2: 51-52. McPheters and Little, 1933, J. Hered. 

 24: 157-158. Kobozieff and Pomriaskinsky-Kobozieff, 1940, Compt. rend. 

 Soc. biol. 133: 386-389. 



Hyperglycaemia and hypoglycaemia. — Griineberg and Haldane, 1940, 

 Nature 145: 704-705. 



Hypotrichosis juvenilis. — The first coat of hair is thin or almost lacking. 

 At 5 weeks the second coat begins to appear and grows in normally, start- 

 ing at the head and progressing tow^ards the tail. Perhaps due to recessive 

 gene, but the percentage of normal overlaps ranges from 3% to 66% in 

 males, higher in females. Loeffler, 1934, Z. ind. Abst.-u. Vererb. 67: 

 209-211. 



Microphthalmia. — Eyes small or opaque, and show various histological 

 abnormalities. Quite variable. Koch and Gowen, 1939, Arch. Path. 

 28: 171-176. 



Palatal ridges reduced. — One pair of palatal ridges missing. Woolley, 

 1937, Rec. Genet. Soc. Am. 6: 176-177. 



Polydactylism. — Occurs in a small percentage of mice in certain inbred 

 strains. Murray, 1932, Science 75: 312. Fortuyn, 1939, Genetica 21: 

 97-106. 



Posterior duplication. — Varying degrees of duplication of structures at 

 posterior end of body. Lethal in extreme forms. Recessive with normal 

 overlaps. Danforth, 1930, Am. J. Anat. 45. 275-288. 



Pseudcncephalie. — Brain defect due to failure of the neural groove to 

 close. Perhaps recessive. Bonnevie, 1936, Norske Videnskaps-Akademi I 

 Oslo. I. Mat.-Naturv. Klasse 9: 1-38. 



Tail tip pigmentation. — White tail tip, inherited perhaps as recessive 

 with normal overlaps. Griineberg, 1936, J. Genet. 2)3,'- 343^345- 



