Strobilus in A rchegoniate Plants. 355 
ancestry, and I see no sufficient reason for doubting this view. 
I am fully impressed by the great remoteness of their origin 
in point of time, and by the absence of a sufficient geological 
record which would throw direct light on their descent. 
There appear, however, to be two other foundations for 
opinion on this question, viz. close examination of the indi- 
vidual development and physiological position of the Vascular 
Cryptogams, and comparison of the Bryophyta. We are, 
I think, bound to use our knowledge of the Bryophyta as 
a guide to an idea of how the more complex Vascular Crypto- 
gams came to be. It may be a question how far the Bryo- 
phytes, as we see them now, illustrate what was the actual 
line of descent of Vascular plants : the similarities may be 
merely those of analogous forms : but we have among other 
living plants no better guide, and it would be nothing short of 
culpable neglect to leave aside the line of analogy which the 
study of the Bryophytes suggests. And as we see in them 
a sequence of forms starting from those in which the sporo- 
gonium is of simple form and almost entirely (in certain Algae 
entirely) devoted to the duty of spore-production, so we may 
believe that the more complex Vascular Cryptogams had 
a similar origin : this is in fact substantially the current 
opinion. We may accordingly contemplate the origin of 
plants with discrete archesporia and appendicular organs, 
from plants with concrete archesporium, and simple form of 
the sporophyte. First, we may consider the biological advan- 
tages which must have followed from the advance of com- 
plexity. We have already recognized the advantage gained 
in archegoniate plants by increased output of spores, and 
noted the advance among the Bryophyta, and some of the 
simple devices adopted by them to meet the demands of 
nutrition and dispersal of their numerous spores. Throughout 
that series, however, the nourishment of the sporophyte is 
mostly received at second hand, the application of its sterile 
tissues to the vegetative office of nutrition being only imper- 
fectly carried out. In the Pteridophyta, however, the nutrition 
is supplied by the sporophyte itself, after the first embryonic 
