METAMORPHOSIS. 



209 



pollen -grains (microspores). Goebel observed in 

 Begonia tuberosa the formation in this position of 

 pollen- mother-cells instead of embryo-sacs (mega- 

 spores). Salter observed pollen-bearing nucelli in the 

 passion-flower (Passiflora), and Masters the same 

 phenomenon in Rosa arvensis. 



The same conclusions may be applied here as were 

 drawn from the phenomena of carpellody of the 

 stamen. 



Carpellody of the ouide may be the interpretation of 

 a phenomenon described by Masters in which a com- 

 pletely-formed carpel, bearing a long style and a 

 stigma, was borne at the top of an otherwise normal, 

 ovuliferous placenta of Primula. It seems to be quite 

 possible for an ovule (i. e. a leaflet) to develop into an 

 independent leaf, equal in size and similar in construc- 

 tion to the leaf of which it is a part. A lateral lobe 

 of a leaf has sometimes equalled in development the 

 leaf itself, and tins might well become the case in 

 Primula where the ovular leaflet is practically sepa- 

 rated from its parent carpel.* On the other hand 

 this terminal carpel may merely represent the first 

 and earliest expression of a proliferation of the central 

 axis. 



(5) Sporophylls of Cryptogams. 



Phyllody. — The sporophylls of the majority of ferns 

 are normally f oliaceous ; the fertile fronds of many, 

 however, have no green lamina developed, these having 

 probably been reduced from the f oliaceous type. The 

 fern-sporophyll most likely represents, in a general 

 way, the type from which those of Gymnosperms and 

 Angiosperms have been derived by a process of simpli- 

 fication. 



The completely fertile fronds of certain ferns fre- 

 quently become partially sterile, thus forming inter- 

 mediate structures, as in Osmunda japonica. In the 



* Cf. the fully-formed leaf (e. g. in the mango, vine, Buddleia) representing 

 the extreme development of the ventral lamellse which morphologically are 

 the united basal lateral lobes fused with the midrib of the main leaf. 

 VOL. II. 14 



