METAMOEPHOSIS. 



203 



position of the nucellus or sporangium, whether 

 terminal or lateral to the segment (pinnule). 



In any case the leafy carpel and ovule represent 

 reversionary structures, and the various forms of 

 abnormal foliage-leaves described above are an indica- 

 tion of the method by which the peculiar structure 

 of the normal carpel and ovule has been brought about 

 in the past. 



Again, the structure of the carpel of Gycas strongly 

 supports the ovular theory as above set forth, for it is 

 clear that the ovule of this plant, from its position, 

 corresponds to a leaf -pinna, and the fact that the 

 Cycadean carpel has been derived from the leafy 

 sporophyll of a Ptericlosperm shows (what might in- 

 deed be deduced without this extra piece of evidence) 

 that the ovule of Gt/cas is a metamorphosed leaf-segment 

 or pinna. 



Thus we see how precisely the same structures as 

 are exhibited by these metamorphosed ovules occur 

 as normal structures in the sporophylls of ferns, and as 

 both normal and abnormal structures in the foliage- 

 leaves of Dicotyledons. 



Squamody of Pistil. 



In some of the secondary flowers resulting from 

 fasciation of the male flower of Welwitschia, the centre, 

 where the vestigial pistil normally occurs, was occupied 

 by great numbers of tiny colourless foliar organs 

 which must probably be placed in the category of 

 scale-leaves ; there were transitions between some of 

 these and the stamens. 



2. Sepalody. — This does not often occur. In"clouble" 

 flowers of those Ranunculacese in which a petaloid calyx 

 and no corolla, or a corolla of reduced nature, is present, 

 the carpels are frequently transformed into sepals, as 

 in Anemone. Duchartre observed in an annual larkspur 

 (Delphinium Ajacis) alternating polymerous whorls of 

 sepals and carpels with numerous transitions between 



