NATURE 
\ APR 18 
\ ; I 3 i 
Ae : 
THURSDAY,. APRIL g, ©1914. 
“A VOCABULARY OF EMBRYOLOGY. 
Terminologie der Entwickelungsmechanik der 
Tiere und Pflanzen. NHerausgegeben von Wil- 
helm Roux. Pp. xii+465. (Leipzig: W. Engel- 
mann, 1972.) Price 10 marks. 
HE science of embryology has its own evo- 
Ls lution. Once upon a time it was no more 
than a science of observation; its task was to 
describe the form and structure of the embryo 
during growth, as the naturalist or the anatomist 
had described those of the organism when it was 
grown. Later on, in the light of the cell-theory, 
in the spirit of Darwinism, and with the help of 
Wolff's and Von Baer’s laws, embryology became 
dominated by, even subjugated to, the historical 
method; its chief aim was “to form a basis for 
phylogeny,’ and its chief problems dealt with 
such matters as the retention of ancestral charac- 
ters in embryonic and larval forms, the explana- 
tion on similar lines of functionless or atrophied 
organs, and the discovery of ‘homologies ” 
between cells, germ-layers, and organs, even in 
distantly-related organisms. 
Such, so far as it can be expressed in a sen- 
tence, was Balfour’s attitude towards embryology, 
and so he defined its aims in the preface to his 
great text-book, adding, however, the important 
qualification ‘‘as restricted in the present work.” 
One great problem, or class of problems, he ex- 
pressly excluded, when he spoke of the embryo- 
logical investigations of certain older writers as 
being “mixed up with irrelevant speculations on 
the origin of life.” But inquiries into the charac- 
ter and inner nature of organic processes, and 
speculations on the nature and even the “origin” 
of life, recur continually to men’s minds, and 
upon such inquiries embryological study has a 
bearing, which is by no means to be dismissed 
as irrelevant. So we come to a third, and nowa- 
days important, phase of embryology, in which 
that science has become not merely a morphologi- 
cal, but a physiological, study, and. is accord- 
ingly approached from the side of chemistry and 
of physics, with the aid of the known properties 
of matter and of energy. 
The new and growing conception of embry- 
ology as a ‘dynamic ” .;science,.or series of 
dynamical problems, carries us a long way from 
the older and simpler embryology, with its 
““statical”’ outlook, its concrete description of 
forms and phases of form. It widens out and out 
into ways of experiment and analysis undreamed 
of a generation ago; it leads us, for instance (to 
name but a few names out of many), to the 
NO. 22007 VOL. 93 | 
philosophical inquirtes< of -Piriesch, to the wide 
experimental field of Loeb and his followers, and 
to the general study of ‘developmental mech- 
anics,’’ which has been the life-work of Wilhelm 
Roux. 
But “the house that is a-building is not as the 
house that is built.” In the growth of a young 
science there is a stage when facts are heaped up 
in apparent.confusion, out of which order and 
simplicity presently emerge. For a while, the 
workman is kept busy making his own tools, and 
in the growth of new knowledge and of new ideas 
language itself has to be strengthened by new 
words. 
Common experience, and the Oxford Diction- 
ary, show us how ill the older vocabulary sufficed 
to keep pace with last century’s growth of ideas, 
even in the ordinary affairs of men. To natural 
science Huxley’s generation contributed a new 
language, which we now speak familiarly; and 
once again, in the narrower field of embryology, 
we wake up to find that yet another language has 
become implanted in the old. We had better not 
ask whether all this new nomenclature be essen- 
tial; some of it will doubtless pass away while 
part remains; meanwhile, it has grown -by a 
natural process of evolution, and those must 
learn it who would master the teaching of the new 
schools. So Prof. Roux, with a little band of 
botanists and anatomists, has set himself in a 
true spirit of helpfulness to put in order the new 
terminology, and to teach this new language to 
those who have not learned it by the way. 
His book is a book of reference, a means of 
interpretation, and a bibliographical guide; it is 
a dictionary, and those who find pleasure in the 
reading of dictionaries are few. Yet, after all, 
the book is something more than a book of refer- 
ence or a mere vocabulary, for many of its para- 
graphs amount to short essays, where the student 
will find both information and instruction. This 
is not only the case in some of the larger articles, 
such as ‘“ Entwickelungsmechanik,” ‘“‘Kampf der 
Theile,” etc., but in others also. Take at random, 
for instance, a little paragraph on ‘‘Scherenum- 
kehr,” or “‘ Heterochelie ”’ ; here we have a concise 
introduction to a very singular phenomenon, wit- 
nessed among certain crabs, which ordinarily 
possess, on opposite sides, one large claw and one 
small one; if the former be chopped off, then the 
latter grows into a big claw, and the former big 
claw, after repair, comes to be a little one. The 
crab is perfectly regenerated, but its new form is 
a “mirror-image” of that with which it began. 
The article ends with references to papers wherein 
this phenomenon is discussed in its many curious 
modifications. 
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