80 Mr Bateson & Miss D. F. M. Pertz, Notes on the inheritance 



3. Corolla with two posterior petals (Fig. 2). Flowers like 

 the normal except that the posterior petal is represented by two 

 petals, each more than half the size of the normal one. 



As it may reasonably be supposed that the one posterior petal 

 of Veronica represents the two posterior petals of 5-petalled 

 Scrophulariaceae, these corollas with two posterior petals can very 

 plausibly be considered reversions. At all events, of the various 

 forms seen this is the one which can with most reason be supposed 

 to represent a form actually passed through in the evolution of 

 the species. Hence it is of interest to note that this is the only 

 one of the common variations which is connected with the normal 

 by any considerable number of intermediate forms. In these the 

 posterior petal is more or less cleft into two (Fig. 19). In 

 the lower forms of the variation the place of division is only 

 indicated by a notch. Such a variation is of course an example 

 of the phenomenon of division in a plane about which there is 

 bilateral symmetry, a phenomenon constantly occurring in animals 

 and plants 1 . By reference to the Tables it will be seen that 

 these intermediates occasionally form a fairly high proportion of 

 the abnormal flowers, though even in these cases the complete 

 form of the variation is as a rule the more frequent on the same 

 plant. 



4. Corolla with six petals, two being posterior and two 

 anterior (Fig. 5). These flowers present the peculiarities of 

 both the 2nd and 3rd forms of variation mentioned above. The 

 anterior two petals here also are not infrequently unequal in size, 

 and the division between the two posterior petals may be in- 

 complete (see No. 3). 



5. Corolla with three petals (Fig. 4). In this form the 

 posterior petal is normal. There is no anterior petal, the corolla 

 being completed by two large lateral petals. The appearance 

 suggests that the material usually composing the two laterals and 

 the anterior has been divided by one median division into two. 

 Not rarely there is at the anterior edges of these two petals a 

 band of lighter colour, shewing that the colour still follows the 

 normal distribution of the 4-petalled flower. This is however by 

 no means always the case. 



6. Corolla with two petals (Fig. 20). The whole corolla 

 is here formed of two petals, placed as anterior and posterior 

 respectively. They are of about equal size. 



7. Corolla with four petals set obliquely (Fig. 7). In this 

 form the petals stand as two anteriors and two posteriors, forming 



i See Materials for the Study of Variation, 1894, p. 448. 



