292 SOME NEW BOOKS [ocroBER 
ence is only apparent, or that there is a certain degree of “spécificité.” There 
is no middle way for Professor Bard: it must be yea or nay with spécificité. 
In the first chapter of this little book he contrasts the conceptions of in- 
difference and spécificité in a manner which appears to us exaggerated ; in the 
second chapter (on the hereditary fixity of cellular types in adult organisms) he 
seeks to answer various objections which are suggested by the facts of cellular 
modifications, of regeneration, of heteromorphosis, etc. ; in the third chapter 
he pursues the analogy of cellular species, and traces their establishment in the 
course of development ; in the fourth he shows how his doctrine bears upon the 
general problems of biology ; and finally there is a list of nineteen publications 
in which the author has previously dealt with the question. 
The new series, of which this book is the first, has for its aim ‘exposé 
philosophique des faits généraux et des idées directrices nouvelles,” but though 
“la spécificité cellulaire” has evidently been a directive idea to the author, we 
do not think that he will succeed in convincing many that it is a general fact. 
To argue the question is not possible within our limits, and we can only express 
our opinion that the chief interest of the book is as an illustration of ingenious 
and enthusiastic special pleading in support of a false analogy. We may note 
in passing that there are a number of irritating misprints, e.g. Heckel for 
Haeckel, and Weissmann for Weismann. J. ARTHUR THOMSON. 
A PICTURE-GALLERY OF THE ISOPODA. 
An Account of the Crustacea of Norway, with Short Descriptions and Figures 
of all the Species. By G. O. Sars. Vol. II. Isopoda. Bergen: 
published by the Bergen Museum. Sold by Alb. Cammermeyer’s 
Forlag, Christiania. 
We make no charge to other nations for the use of the English language. 
This generous extension of free-trade does not pass unrewarded. From time to 
time it brings us from abroad noble contributions to English scientific literature. 
It is in our own tongue that we have the satisfaction of reading ‘‘ An Account 
of the Crustacea of Norway,” by the Norwegian professor, G. O. Sars. His 
lifelong studies, embracing in turn the several groups of the crustacean class, 
have given him an almost incomparable facility and trustworthiness as an 
exponent of them all. The first volume of the “‘ Account,” which gave figures 
and descriptions of all the known Scandinavian Amphipoda, has already been 
reviewed in these columns. The intelligent reader, which is only another way 
of saying every reader of Matural Science, will recall something of what was 
then pointed out. It was to the effect that both the large agreement of the 
Norwegian fauna with our own, and the highly instructive handling of it by 
Professor Sars, made his work absolutely indispensable to every serious student 
of the Amphipoda in these islands. A similar remark may be applied to the 
second volume, just completed, which deals with a second order of sessile-eyed 
crustaceans, called Isopoda. 
The name of this group was given it by Latreille in the Middle Ages, that 
is to say, nearly a hundred years ago, when people in general knew and cared 
about crustaceans hardly more than they now know and care about the centre 
of the earth. The name “isopod” signifies an animal with equal legs, and might 
therefore include most men and turkeys and many quadrupeds, though not so 
obviously applicable to the giraffe, the bison, or the kangaroo. But equality 
between legs, applying to two, or four, is less striking than when it refers to 
fourteen, a number with which the Amphipoda and Isopoda are endowed. In 
distinguishing the latter by the character of having equal legs, Latreille chose 
a name suitable enough toa woodlouse, such as Armadillidium vulgare, and to 
not a few of the marine species, such as Sphaeroma serratum, which, like the 
land woodlouse just mentioned, can roll itself into a neat little pill-like ball. 

