The “ Xerophytic ” Character of the Gy innosperms. 47 
it in their individual lives. In short, that their xerophily is 
inherited. To quote Schimper 1 “ die xerophile Structur der 
Coniferen eine erbliche Eigenthiimlichkeit darstellt, welche den 
gegenwartigen Existenzbedingungen nicht immer zu entsprechen 
scheint.” 
As the Ecologists are now showing what wonders can be 
worked in the life of even a single generation of xerophytic plants, 
one is forced to believe that there must be something much stronger 
than an ancient inheritance underlying the well developed, but 
apparently useless, xerophily of so many Gymnosperms. 
Let us first see what grounds there are for assuming that it is 
a character depending on the environment of past ancestors. Both 
from the botanical evidence and judging from analogy with animals 
it would be extremely unlikely that many living species have come 
down from the Eocene to the present day, but for the sake of the 
argument let us look back as far as the Cretaceous. 
Coniferales are recognised as playing an important part in the 
Tertiary floras of which we have any knowledge. The many 
impressions of stems and foliage which have been preserved show 
that their morphology was exceedingly similar to that of the recent 
species. Hence these Tertiary Conifers may be the ancestors which 
have imprinted their habit on those living to-day. But when we 
look at the fossil impressions of the flowering plants associated with 
these Gymnosperms, we find many forms resembling our Maples, 
Beeches and Magnolias, which do not pre-suppose any excessively 
xerophytic character in the environment, with others indicating a 
warm and even protected habitat. Further, it is known from the 
plants found in the Tertiary deposits of such places as Spitzbergen 
that similar conditions prevailed even far north, and they point to a 
widely spread mild climate and luxuriant flora. Also in the 
Cretaceous we find a similar relation between the plants, the 
Coniferales resembling the recent ones in their xerophytic 
character, but living associated with mesophilous plants which 
apparently flourished under no excessive drought conditions. 
We are therefore left with the Cretaceous and Tertiary Gym¬ 
nosperms in just the same position as with regard to the modern ones, 
viz., that their environment offers no apparent explanation of their 
xerophilous structure. It is true that the earlier Gymnosperms, 
right back to the earliest known Palaeozoic, also show xerophytic 
structure; but to consider that a purely Ecological adaptation 
should have been transmitted through the many changing species 
which lie between these ancient Gymnosperms and even their 
1 Schimper, A. W. “ Pflanzengeographie.” Jena, 1898, p. 595. 
