COHESION AND SUPPRESSION. 263 



gressive feature in the Orcliidaceae and Oleaceaj, the 

 probabilities are in favour of this condition being also 

 progressive, and not reversionary, in all other orders 

 •where it obtains, e. g. Cruciferge and, Papaveracese, for 

 the law of reduction reigns universally throughout the 

 Angiosperms. 



Hence, Celakovsky would appear to be right in 

 holding that the most primitive type of flower is that 

 in which the pleiomerous condition prevails in all parts 

 of the flower, and in which the floral leaves, from calyx 

 to pistil, are arranged spirally and not in verticils. 

 The abnormal increase in the number of whorls and of 

 members composing them must therefore be regarded 

 as, in the great majority of cases, due to reversion to 

 an ancestral condition. In the. case of the tulip and 

 lily the dual tendency was manifest to revert to a larger 

 number of members and to the spiral arrangement 

 thereof ; the 4 + 4 condition of the tulip corresponds 

 to the spiral series f , the 5 + 4 to the series f , the 

 4 + 3 (so common in the androecium) to the series 

 y. The Monocotyledonous flower of the ordinary type, 

 e. g. the tulip, has almost certainly been reduced from 

 a more complex type, probably from that found in 

 .such plants as the Berberidace^ and Magnoliacese in 

 which both calyx and corolla have more than one 

 whorl of three. For instance, the K5 C5 of some tulip- 

 and lily-flowers (really representing in each whorl a 

 congestion of two : K2 + 3 C2 + 3) has nearly reached 

 the presumed ancestral condition which is to-day 

 exemplified in Berberidacege, etc.: K3 + 3 C3 +3^ 

 From this the typical Dicotyledonous flower is but one 

 step removed by reduction, the floral formula being : K5 

 C5 A5 0-5, which is that of our pentamerous tulip. In 

 the typical Dicotyledonous flower the whorl of five pro- 

 bably represents a congestion of two whorls of two and 

 three each, a fact which is generally recognized, at any 

 rate for the calyx. 



We may conclude, therefore, that both in the normal 

 and the abnormal phenomena in which reduction, 



