C. E. Moss. 
183 
Two other species of Rhizophora were examined and similar 
results were obtained. The structure was similar to that of the 
Rhizophora obtained from Mombasa. 
Although perhaps this study was not a very exhaustive one, it 
is probably safe to assume that in the Rhizophoraceae generally 
the hypocotyl is an assimilatory organ, and is definitely modified 
for assimilatory purposes, and this is certainly true for the species 
investigated. 
In conclusion I wish to say that my thanks are due to 
Professor Weiss, who supplied me with material, and from time to 
time kindly gave suggestions as to the method of doing this work. 
XEROPHILY AND THE DECIDUOUS HABIT. 
fMHE communication of Miss Stopes' on the Xerophily of the 
is Coniferales, raises several interesting matters. With her 
general contention, that the xerophily of the Coniferales is inherited 
and not acquired, I do not propose to deal, as Miss Stopes amply 
proves her case. There is, however, an important modification of 
this argument to be made before it can be regarded as applicable 
to the whole family ; and there is, running through the whole of 
Miss Stopes’s article, an assumption with which I do not agree. 
This assumption is that the xerophily of the Coniferales is 
more pronounced than the xerophily of deciduous dicotyledonous 
trees, that the xerophily of the Coniferales is out of place at the 
present time in a mixed, deciduous forest. For my part, I regard 
the Coniferales as possessing one particular kind of xerophily, and 
the deciduous, dicotyledonous trees as possessing another; and the 
xerophily of the latter species appears to me to be quite as effective 
as, if not, in fact, more effective than the xerophily of the former 
species. The xerophily of the Coniferales, is seen, as Miss Stopes 
points out, in the “ xerophytic leaf,” and in the whole structure of 
the wood, especially in the small diameter of the tracheides. The 
xerophily of the dicotyledons, I maintain, is seen in the deciduous 
habit, which, during the winter season, reduces transpiration 
to zero. 
Taking the Scots pine ( Pinus silvestris ) and the birch ( Detain 
alba) as well-known British examples of the conifers and the 
1 Stopes, M. C. “The Xerophily of the Coniferales,” New 
Phytologist, February, 1907. 
