248 Bower. — Imperfect Sporangia in certain 
I think the latter view is the more probable one. It is 
apparent from the various memoirs on embryonic Lycopods 
that the initial plan of the embryo is essentially the same for 
all the species described ; and that the differences depend 
upon different proportional development of the parts, and 
difference in the time of their first appearance. Where one 
part is largely developed at an early period, others are 
apt to be delayed, or to be developed on a smaller scale : 
in fact the principle of correlation holds in the embryo as 
elsewhere. As examples, in Phylloglossum (which may with 
propriety rank with the embryonic Lycopods) the large 
protocorm is formed before either protophylls, roots, or 
strobilus are initiated. In L. cernuum and inundatum the 
root and leafy shoot appear late, though the protocorm and 
protophylls which appear early are of relatively large size. 
In L. clavatum and annotinum the foot is very large and the 
axis early developed, but the first leaves are small and the first 
root appears rather late. On the other hand, in L . Selago , 
where no disproportionately large protocorm or foot is formed, 
axis and leaf are defined relatively early, and the root soon 
follows. Are then the protocorm or the specially enlarged 
foot really primitive parts of the embryo, or disturbing in- 
fluences introduced only in special cases to meet special needs? 
Was it once universal in Lycopod embryos, and is it therefore 
necessary to explain by abortion the absence of such paren- 
chymatous swellings in certain species 1 , and especially in 
L. Selago , which, as we have seen, shows in other respects 
1 Dr. Treub has quoted certain embryos of L. Phlegmaria , as showing what he 
regards as a rudimentary protocorm (Buit. Ann., viii, p. 32). In his paper on this 
species (Buit. Ann., v) he has shown on PL XXVI, in a series of embryos, a 
rounded swelling (P), in the position in which the protocorm appears in the 
cernuum type: it may, under circumstances, form rhizoids (Fig. 4), but soon the 
true root forms at the apex of the protuberance. It is possible that this may 
be a rudimentary protocorm, but I do not think the facts conclusive ; for the root 
appears exogenously just at the point of greatest convexity of the swelling ; more- 
over, in L. cernuum, as in Phylloglossum , which have typical protocorms, the root 
does not appear on the tip of the protocorm (which would thus be its position if 
the swelling in L. Phlegmaria be really a protocorm), but in the upper region 
nearer the leaves. 
