DICHOTOMY. 103 



termed " budding." Very little experience enables an 

 observer to distinguish between a dichotomized ray and 

 a bud. 



In 1831 Tiedemann r published a brief description of a 

 star-fish, Asterias equestris Linn, with a partially dicho- 

 tomized ray, and pointed out that it must be regarded as 



FiG. 51. A, Star-fish with a completely dichotomized ray ; 

 B, a larger ray partially dichotomized. 



a malformation and not regeneration, as is so frequently 

 the case with star-fish. 



Dichotomy occurs also in the appendages of the skin. 

 Few parts seem more distinct than feathers and 

 teeth, yet a study of the manner in which these 

 J " Zeitschrift fur Physiologic," Bd. iv. p. 121, 



