60 



PRINCIPLES OF PLANT-TERATOLOGY. 



be grouped under three main stages, each representing 

 a further step backwards towards the ancestral con- 

 dition : (1) increase in number of the members of a 

 whorl ; (2) increase in the number of whorls ; (3) these 

 two resolved into a spiral arrangement of the floral 

 members. Nageli was the first to point out that this 

 arrangement is the most primitive and preceded the 

 cyclic; Engler, on the other hand, maintaining that 

 both are equally old. 



As a type of a flower exhibiting this phenomenon 

 the garden tulip (Tulipa Gesnericma) may be taken. 

 Several kinds of polyphylly are seen in this flower : it 

 may affect one, two, or three of the whorls only, the 

 the others being normal ; very often the whorl so 

 affected is the pistil, as in flowers in which an extra 

 carpel was added, giving the formula K3 C3 A3 + 3 G 4 ; 

 in another flower there were six carpels, apparently 

 all in one whorl ; in another there were nine carpels, 

 an outer of six, an inner of three, arranged in two 

 whorls ; in a flower of the wild tulip {T. sylrestrh) 

 the formula was K4 C4 A4 f 3 G 3 ; in one of T. tri- 

 pht/lla K4 C4 (one petal half-staminoid) A4 + 3 G 4 , in 

 which all the whorls save one of the staminal whorls 

 had been increased by one. In these examples we see 

 irregularity and apparent lack of any clearly-defined 

 method in the process of increasing the whorl-members. 

 In other cases, however, the change takes place more 

 uniformly, and in many instances as if governed by 

 some fundamental law. In some flowers of the garden 

 tulip there was an increase of one only to all the 

 whorls except the pistil, which had two added to it : 

 K4 04 A4 -f 4 G 5 . A Crocus may be mentioned in 

 which the number in each of the whorls w T as increased 

 by one : K4 C4 A4 G 4 ; in another it was increased 

 by two : K5 C5 A5 G 5 , giving a structure like that of a 

 typical Dicotyledonous flower. Buchenau describes 

 exactly the same thing in Lilium croceum. 



In the herb Paris the flower is normally 4-merous, 

 at least in P. quadrifolia and other species. But 5- and 



