H3 
of the terms ‘ Phyllome ’ and 1 Caulome ! 
The evidence that such a parallel differentiation of the 
shoot has actually taken place is of the strongest possible 
kind, and is based primarily upon the researches of Hof- 
meister, by whom it was first demonstrated that the Moss- 
plant corresponds in its position in the life-cycle not to the 
Fern-plant, but to the Fern-prothallus. Taking first the 
sporophore generation in such a series of forms as Coleochaete , 
Anthoceros , Phylloglossum , a Fern, and a Phanerogam, we 
should in them see broadly indicated the rise of the sporo- 
phore generation ; it is true the series is defective, the gap 
between the non-foliar sporophore of Anthoceros and the foliar 
one of Phylloglossum or of a Fern is a wide one; but there can 
be no reasonable room for doubt that the differentiation of the 
shoot into caulome and phyllome was a gradual one, though 
the intermediate forms have dropped out of existence. This 
view is strongly supported by analogy of the oophore ; here, in 
such a series of types as Pellia , Blasia , a leafy Jungermannia , 
and a Moss, we have illustrated a similar but quite distinct 
differentiation of the shoot of the oophore generation ; the 
two processes of differentiation, taking place at different 
points in the life-cycle, must necessarily have progressed 
independently of one another, and all the knowledge we 
possess of the plants concerned confirms this view 1 . Accord- 
ingly, notwithstanding the apparent similarity in external 
conformation, the ‘leaf 5 in the oophore is not the lineal 
descendant of the leaf in the sporophore : thus we can only 
recognise the parts of the shoot in the sporophore and oophore 
generations as morphologically analogous to one another ; the 
two are ‘ homoplastic , 5 but not morphologically homologous. 
This being so, I think it is desirable in the interests of clearness 
present sense. The same may be said of the terms stem and leaf, which may still 
be accepted in a general sense as applicable to corresponding parts of oophore or 
sporophore generation. 
1 The notable fact of the similarity in external conformation of the oophore and 
young sporophore in Lycopodium cernuum and inundatum presents no obstacle 
to this view : it would appear that the differentiation had taken place both in 
oophore and sporophore, but still the process of differentiation might have been 
independent in the two generations. 
