ii] Structural Characters: Animals 33 



be a recessive, the presence of normal fur being a dominant. 

 The fur grows at first normally and falls off as maturity is 

 reached. Of 12 F z mice 3 lost their hair. I am indebted 

 to Mr Campbell for information respecting this interesting 

 case, and for living specimens. The attempt to breed the 

 recessives together failed, but in Gaskoin's case* naked 

 parents produced young like themselves. From his account 

 it appears that the young which he observed never grew 

 their hair, but the fact is not absolutely certain from the 

 description. 



40. The normal condition and the ''waltzing" habit in 

 Japanese mice. The waltzers exhibit a peculiar vertiginous 

 movement of the head when they come out into the light, 

 and spin often with extreme rapidity, running after their 

 tails till apparently exhausted. 



Our knowledge of this case is derived from Von Guaita 

 (135) and Darbishire (90). The dominance of the normal 

 type is complete, and in F. 2 waltzers reappear. The F ., 

 numbers obtained by Darbishire were 458 normals, 97 

 waltzers, where the expectation is 386 normals, 139 waltzers. 

 The deficiency may perhaps indicate a complication, but 

 more probably it is due to the greater delicacy of the 

 abnormal mice, which was so great that all attempts to 

 breed them together were unsuccessful. 



RABBIT, GUINEA-PIG. 



41. Normal short hair and the long "Angora" hair 

 Rabbit, Guinea-pig, and doubtless Cat (see Hurst, 157 ; 

 Castle, 45 and 48 ; Sollas, unpublished ; Castle and 

 Forbes, 55). 



Castle (48), p. 64, gives important details as to the physiological nature 

 of the distinction between the normal and "Angora" hair, which he regards 

 as resulting from a special method of growth. 



42. The rough or resetted condition of the coat in the 

 Guinea-pig dominates over the normally smooth condition 

 (Castle, 48 ; Sollas, unpublished). 



Castle found occasionally that animals partially resetted occurred in F z . 



* For references see Bateson, Materials for Study of Variation, 1894, 

 p. 56. A good figure is given by Gaskoin, Proc. Zool. Soc. 1856. 



B. H. * 



