226 
will be struck by the resemblance in organisation of the 
synangium Telangium on the one hand and the seed on 
the other. 
, The chambers surrounding the nucellus seem to represent 
its sister sporangia, which have become sterile, the large- 
celled, thin-walled tissue and delicate vascular strand being 
all that represents the ancestral sporogenous tissue; while 
the micropyle corresponds ‘with the original space between 
the tips of the sporangia. The seed in fact is assumed to 
be a synangium in which all but one of the sporangia 
are sterile, and form an integument to the one fertile 
sporange which has become a megasporange with one 
large megaspore. In Lagenostoma physoides the integu- 
mental ridges are continued into tapering tentacles around 
the micropyle, and this still further accentuates the resem- 
blance to a sorus” (p. 169). ,Hence we have only to 
imagine that one of the sporangia of a sorus of eight or 
ten sporangia gradually evolved megaspory, and that the 
remaining seven or nine sporangia became a sterile 
envelope” (p. 169). 
Here we have the whole so-called synangial-theory, 
which is based entirely on the undeniable resemblance 
between a synange and a seed, but which has this great 
disadvantage, that nothing of it is duely established and 
that the evidence of the facts is too meagre, to allow 
the drawing of such far reaching conclusions. 
It occurs in several fern-sori, that some synangia remain 
sterile and are scattered amongst the others as paraphyses, 
but that the middle-one should always be fertile and the 
surrounding sporangia sterile, to form a closed outer 
envelopment, is quite unknown as a rule in any plant. 
Oliver (104) therefore opposes this opinion of Miss 
Benson and regards the integument as being a 
new structure. He compares the fructifications of the 
Pteridosperms rather with those of Lepidocarpon and 
