2 I 8 
Review: 
probably two lines of evolution from a more primitive form. If the 
larva reproduced itself asexually before forming the imago we 
should have a condition of things similar to alternation in plants, 
and if the larva and imago, in some cases, were to start life under 
different conditions we should have a relation exactly parallel to that 
of the Archegoniatae. It is quite possible that some such history as 
this has been that of the origin of Pteridophyta; and in fact it is 
the ordinary homologous theory. It is interesting to note that the 
more elaborate and phylogenetically later body (larva and sporo- 
phyte) is in both cases first produced from the egg, the more 
primitive (sexual imago and gametophyte) coming later in the cycle. 
REVIEW. 
“The Oecology of Plants, an Introduction to the Study of 
Plant Communities, by Eug. Warming, assisted by Martin Vahl, 
prepared for publication in English by Percy Groom and Isaac 
Bayley Balfour.” Oxford, at the Clarendon Press, 1909. Pp. XI. 
and 422. Price 8s. 6d. 
1HE first feeling aroused on opening this book is one of regret 
1 that an English edition of Professor Warming’s “ Plantesam- 
fund ” was not issued at least ten years ago. In the early nineties 
of the last century plant-ecology was but little pursued in this 
country and formed practically no part of the University curricula. 
The subject was indeed in so rudimentary a condition that available 
material scarcely existed for teaching purposes. To show students 
a few sections of xerophytes and water-plants was about the most 
that could be attempted. Professor Warming’s “ Plantesamfund,” 
rendered available to the majority of English botanists in Knoblauch’s 
translation, published in 1896 under the title “ CEcologische 
Pflanzengeographie,” was the first general text-book on the study 
of vegetation in its relation to environment, and a most excellent 
account it was. Systematically arranged, clearly written, and 
remarkable for its penetrating and judicious treatment of difficult 
and obscure topics, it formed a very admirable guide to this 
fascinating subject, as it existed fourteen years ago. Its immediate 
translation for the benefit of English students was quite obviously 
called for. “ The difficulties opposing its production ” are somewhat 
mysteriously alluded to in the prefatory “note” to the present 
volume. Whatever they may have been, we can only regret that 
they were not successfully overcome long ago. For the present 
work, excellent as it is in many ways, cannot be said to stand in the 
same relation to the subject as did the “Plantesamfund” in 1895. 
Plant-ecology has developed enormously in the interval, both in 
