74 



PRINCIPLES OF PLANT-TERATOLOGY. 



About halfway up the tube, on the inner surface, are 

 given off five supernumerary petals, opposite to as 

 many lobes of the corolla. Some of the supplementary 

 petals have a stamen in front of them, in the same 

 relative position as in the normal flower. In some 

 cases the back or outer surface of the supplementary 

 petal is turned towards the inner or upper surface of 

 the primary corolla, thus ^ ; while, in other instances, 

 the front of the adventitious lobe is directed towards 

 the corresponding surface of the original petal, thus 

 O. Whether these supernumerary petals are formed 

 by chorisis or by enation cannot, with certainty, be 

 determined without examining the early stages of 

 development." In this case we have the converse of 

 that of Gloxinia, for here the outer lobes of the dividing 

 petal-rudiments must have developed more strongly, 

 and therefore ahead of, the inner, whereby the latter 

 came to appear at maturity as mere branches or 

 appendages of the former. 



In Datura, " Gloxinia " Primula, and similar plants, 

 the phenomenon described probably consists of an 

 imperfect attempt on the part of tke flower to form a 

 second corolla* by the process of serial dedoublement, 

 and this takes a varying form according to the idio- 

 syncrasy of the flower or plant concerned. The 

 phenomenon represents, therefore, a first step in 

 doubling. From its consideration we see that there is 

 not, as the older writers like Masters supposed, an essen- 

 tial distinction between " enation " and " chorisis," 

 for both are but manifestations of one and the same 

 phenomenon under different circumstances. Moreover, 

 the statement that one organ is an " enation 5 from 

 another is a purely descriptive one and sheds no light 

 on the real nature of the phenomenon. 



In Symphytum, and " Gloxinia " we see the two 



* It may be, however, that in "Gloxinia" the " enations " may be the 

 relic of an extra corolla ; the present-day plants may be the descendants of 

 a strain possessing two complete and independent corollas which was 

 formerly in cultivation and has now become obsolete. This seems to have 

 been Masters' view. 



