26 



NA TURE 



[May 9, 1901 



as on Fahrenheit's original scale, so that the scale now 

 known by his name differs slightly from that originally 

 defined by him. Two of his original instruments are in 

 the Physical Laboratory at Leyden ; the freezing points 

 as now given by them are at 34^'2 and 34""! respectively ; 

 both of these are mercury thermometers. 



After Fahrenheit's time came various imitators, each 

 with his own special scale ; for an account of them we 

 must refer the reader to Mr. Bolton's pages. Among 

 them the scales of Reaumur and of Celsius alone survive, 

 though, as Mr. Bolton points out, Celsius proposed to 

 call the boiling point of water o' and its freezing point 

 100^ ; the change to the present centigrade scale was 

 made independently in 1743 by Christin, of Lyons, and 

 seven years later by Strtimer, a colleague of Celsius at 

 Upsala. 



Reaumur's choice of 80' for the temperature of steam 

 was made as a result of his experiments on the expansion 

 of alcohol. He found that alco'hol, diluted with one-fifth 

 water, expanded in volume from 1000 to 1080 when 

 raised from the freezing point to the boiling point. 



Mr. Bolton is to be congratulated on his work. He has 

 made it most interesting, and it deserves many readers ; 

 it suggests the hope that some one may take up similarly 

 the history of other physical instruments and write about 

 them in as bright and capable a manner. 



THE OXFORD TEXT- BOOK OF ZOOLOGY. 



A Treatise on Zoology. Edited by E. Ray Lankesler 

 Part IL The Porifera and Coele?itera. By E. A. 

 Minchin, G. H. Fowler and G. C. Bourne. With an 

 introduction by E. Ray Lankester. Pp. x + 405. 

 (London : Adam and Charles Black, 1900.) 



THE second part of the "Treatise on Zoology," now- 

 appearing under the editorship of Prof. Ray Lan- 

 kester, contains six chapters, the work of four different 

 authors, graduates of the University of Oxford. An 

 introductory chapter by the editor, on the Enteroccela 

 and Ccelomocoela, deals with the main divisions of the 

 Metazoa ; Prof E. A. Minchin writes on the Sponges ; 

 Dr. G. H. Fowler on Hydromedusa? and Scyphomedusje ; 

 and Mr. G. C. Bourne on the .Anthozoa and Ctenophora. 

 The high character of the whole work, of which the 

 volume previously published (Part 11 L Echinoderma) gave 

 promise, is fully established by that now before us, and 

 it can scarcely be doubted that this treatise will, for some 

 time to come, be regarded as the standard English text- 

 book for advanced students of zoology. 



The classification of the Metazoa adopted by Prof 

 Lankester in the introductory chapter is based upon the 

 work of the most recent writers on animal morphology, 

 and differs in several ways from that previously adopted 

 in the text-books. The whole animal kingdom having 

 first been divided into two grades, the Protozoa and the 

 Metazoa, the grade Metazoa is considered as giving rise 

 to two branches, the Parazoa, or Sponges, and the 

 Enterozoa, the latter name being a term previously in- 

 troduced by Prof Lankester as a substitute for Haeckel's 

 term Metazoa, but which he now proposes to restrict to 

 the second great division of the Metazoa. The view thus 

 adopted of the position of Sponges in the animal kingdom 

 NO. 1645, VOL. 64] 



is that advocated by Minchin in the present work (see 

 p. 158) ; but, as that author points out, it is one which 

 is by no means accepted, at the present time, by other 

 leading authorities on the morphology of the Porifera. 



After this main division of the Metazoa, Prof Lankester 

 proceeds to divide the Enterozoa into two branches, the 

 Enteroccela, or those in which the sole cavity is the 

 enteron, and the Cctlomoccela, those in which the coelom 

 is present as an independent second cavity. It is cer- 

 tainly open to doubt whether any advantage is gained 

 by the introduction, in a work of this character, of these 

 new terms to replace the already so widely used Ccelentera 

 (or Cuelenterata) and Ccelomata. Indeed, Prof Lankester 

 himself appears to regard his new nomenclature as ten- 

 tatively put forward for the consideration of his fellow 

 morphologists, for it is not even adopted in the present 

 volume. The title-page bears the name Ccelentera, and 

 this is the term used both by Mr. Bourne and Dr. Fowler 

 in their sections of the work, the latter writer making 

 use also of the form Ccelenterata (p. 60), to which the 

 editor of the treatise takes exception. 



The remaining portion of the introductory chapter 

 gives, in a clear and interesting manner, an account of 

 the author's views with regard to the ccelom and its re- 

 lations to the other cavities of the body in the different 

 phyla of the Ccelomata (Ccelomocccla), together with a 

 detailed history of the progress of our knowledge of that 

 organ. The discussion of this subject is noteworthy on 

 account of the particularly clear statement of the author's 

 theory of the body-cavity relations found in the MoUusca 

 and Arthropoda. According to this theory, now termed 

 the theory of Phleba^desis, the true crelom is present 

 in these groups in a reduced form, whilst the blood-holding 

 spaces (h;emocctl) are in reality swollen blood-vessels. 

 In support of this view, Benham's work on Magetona 

 {Oitart. Journ. Micr. Sci., xxxix. 1896) is brought forward. 

 The concluding part of the chapter is of interest from 

 the great importance attached to the recent work of 

 Meyer and of Goodrich on the nephridia and cct-lomoducts 

 of the marine Ch;etopoda, the views of these authors being 

 entirely adopted, notwithstanding the fact that they re- 

 volutionise the prevailing ideas on the subject, ideas 

 which owe their origin very largely to Prof. Lankester 

 himself. 



Prof Minchin's section on the Sponges, we have little 

 hesitation in saying, contains the most successful account 

 of an animal group which has yet appeared in this treatise. 

 It is in many ways a model of what such a general ac- 

 count should be, and is certainly the most satisfactory 

 summary of our knowledge of the Porifera which at 

 present exists in any language. It is by no means 

 merely a compilation and discussion of facts already put 

 on record by other authors. Much new matter is here 

 recorded for the first time — notably the account of the 

 development of Clathrina blanca — and a large part of 

 the descriptive portions of the chapter is the direct out- 

 come of the author's own observation and experience. 

 Prof Minchin's work as a histologist, which has shown 

 him to be an expert in the most recent and delicate 

 methods of technique, is well known, but the present 

 article proves him to be at the same time a painstaking 

 and observant outdoor naturalist. That a sponge is a 

 living organism and that each species is specially adapted 



