132 



PRINCIPLES OP PLANT-TERATOhOaY. 



held that the reverse phenomenon was occurring, viz., 

 that bracts were being formed from the calyx, for the 

 number of stamens had increased from six to eight, 

 indicating that it had been found necessary to trans- 

 form two inner perianth -leaves (corresponding to the 

 two extra sepals derived from bracts) into stamens. 

 The extra stamens cannot otherwise be accounted for. 

 Hbteeosepalody. — In some zygomorphic flowers 

 there are two kinds of sepals in the flower : the 

 ordinary ones and those which are spurred. The 



Fig. 115. — Delphinium Ajacis (Annual Lartspur). Flower with two 

 extra sepal-spurs. Diagram. (After Hraun.) 



abnormal change consists in the metamorphosis of one 

 kind into the other. 



Spur -formation. — In Delpliiiiium, e. g. D. Gonsolida, 

 the posterior sepal only is normally spurred ; in 

 abnormal flowers one or more extra sepals may be 

 spurred (fig. 115), even all five sepals may be spurred. 

 Just the same kind of change may occur in the 

 monkshood [Aconituvi.). In the Indian cress {Tropseo- 

 lum maj'UH) two spurs were seen; they were situated 

 between the posterior and lateral sepals ; normally 

 there is a single spur in the median posterior position, 

 which is often regarded as being formed by the whole 

 of the median and by half of each lateral sepal, hence 

 the phenomenon just mentioned may be due to the 



