54 DISCONTINUOUS VARIATION. 



that these discontinuous meristic variations are not only 

 large, but they are complete and perfect. But after 

 all one would scarcely expect anything else. Between a 

 six petal and a seven petal flower it is scarcely pos- 

 sible to imagine such a thing as a really intermediate 

 stage. Even if one found a flower with six normal 

 petals and a seventh abnormally small one, or five nor- 

 mal ones and a sixth in process of dividing into two, 

 one would scarcely be justified in regarding it as an in- 

 termediate form, for the flower would no longer be sym- 

 metrical. 



Perhaps the most interesting part of Bateson's work 

 lies in the cases which he has collected of what he terms 

 Homceosis. By this he means those variations which 

 consist in the assumption by one member of a meristic 

 series, of the form and characters proper to other mem- 

 bers of the series. For instance, Kraatz has described 

 a saw-fly, Cimbex axillaris, having the peripheral parts 

 of the left antenna developed as a foot, the right an- 

 tenna being normal. Kriechbaumer has described a 

 nearly similar condition in a Humble-bee, Bombus 

 variabilis. Bateson has himself described a crab, 

 Cancer pagurus, having the right third maxillipede de- 

 veloped as a chela. Milne-Edwards has described an- 

 other crab, Palinurus penicillatus, in which the left 

 eye bore an antenna-like flagellum several centimetres 

 in length, growing up from the surface of the eye. The 

 eye stalk appears to have been of normal shape, but re- 

 duced in size. Other instances somewhat similar to 

 these are adduced, but it is unnecessary to quote them 

 here. It may be mentioned, however, that most inter- 

 esting examples of this form of variation have been 



