160 
THE PERN FAMILIES OF BRITAIN. 
able to observe tbe formation of young Fern-plants on these 
protballi; but it may be hoped that from cultures now in 
progress at Kew and elsewhere further evidence may be 
obtained on this point. 
This Polystichum is thus an example of the formation of an 
expansion of undoubted prothalloid nature, bearing sexual 
organs by a process of purely vegetative outgrowth from the 
Fern-plant — that is, there is a transition in this case from 
the sporophore generation to the oophore by a vegetative 
growth, and without any connection either with spores or, 
indeed, with sporangia or sori. It may be regarded as a still 
more complete example of apospory than that of Athyrium 
Filix-foemina, var. Clarissima. 
