292 SOME NEW BOOKS [ootober 



ence is only apparent, or that there is a certain degree of "specificite." There 

 is no middle way for Professor Bard : it must be yea or nay with specificite. 



In the first chapter of this little book he contrasts the conceptions of in- 

 difference and specificite 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 " l'expose 

 philosophique des faits generaux et des idees directrices nouvelles," but though 

 " la specificite 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. 0. 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 Natural 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 to a 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. 



