MUTATION 171 



pable of vigorous transmission. The frequency 

 of such mutations depends on the number of 

 individuals studied. 



Now, during the past four years I have bred, 

 handled, and described over ten thousand poul- 

 try of known ancestry. Of striking new char- 

 acters I have observed many, some incompatible 

 with normal existence; others in no way unfit- 

 ting the individual for continued hfe. In the 

 egg, unhatched, I have obtained Siamese twins, 

 anteriorly duplex individuals with shortened 

 upper jaw (like that of the niata cattle, pug 

 dogs, and some carp), and chicks with thigh 

 bones absent. There have been reared chicks 

 with toes grown together by a web, without toe- 

 nail or with two toe-nails on one toe; with five 

 toes, six toes, seven toes, or three toes; with one 

 wing lacking or both absent; with two pair of 

 spurs; without oil-gland or tail (though from 

 tailed ancestry) ; with neck nearly devoid of 

 feathers; with cerebral hernia and a great crest; 

 with feather shaft curved ; with barbs twisted and 

 dicotomously branched, or lacking altogether. 

 Of the comb alone I have a score of forms : single, 

 double, triple, quintuple, and walnut, V-shaped, 

 cup-shaped, comprising two horns or four or six, 

 absent posteriorly, absent anteriorly, and absent 

 altogether. All of these conditions have been 

 offered me without the least effort or conscious 

 selection on my part, and each appeared in the 

 first generation as well developed peculiarities, 



