January 2, 1896] 



NA TURE 



195 



A very noticealDle feature of the volume is the large 



pace devoted to the consideration of the Liverworts. 

 is quite surprising how little attention botanists have 

 en accustomed to pay to this group ; many are quite 



intent with acquiring a knowledge of Marchantia, 

 which, as it happens, is a very specialised form, and not 

 in the least degree typical of Liverworts taken as a whole. 

 This neglect becomes the less intelligible when one con- 

 siders the extreme diversity of outward form exhibited 

 even within the limits of a single genus, a diversity only 

 perhaps paralleled by some genera of lichens, or of 

 alga. And again, their position at the base of the 

 archegoniate series should have sufficed to rescue them 

 from a condition of such unmerited oblivion. Thus 

 the author has done good service by devoting 140 

 pages to the Hepaticae alone. It is, perhaps, to be 

 regretted that he did not lay more emphasis on the 

 extent of morphological specialisation which may be 

 observed amongst the species of individual genera ; 

 thus, for example, all gradations may be traced in forms 

 included in Symp/tyogyna, from a creeping fiat thallus to 

 a complicated branch system, recalling that of the 

 sporophyte of many HymenophyllaceiTe. No doubt 

 this would have entailed an increased number of 

 pages, but, we think, the addition would have been 

 \ cry welcome. 



We notice one or two slips here and there. Thus it is 

 stated on page 97 that all the acrogynous Jungermanniacese 

 possess a three-sided apical cell, whereas at least one 

 bpecies of Physiotiiun is known in which the cell is 

 lenticular in transverse section. But these are but trivial 

 errors, and the general summing-up of the Hepaticae 

 strikes us as extremely good, even though we may hesitate 

 Ijefore accepting all the author's conclusions. 



The \'ascular Cryptogams are treated very fully, as one 

 \\ ould have expected from a writer who has himself con- 

 tributed so much to our knowledge of the group. But 

 occasionally, if we may venture to say so, the investigator 

 is perhaps a little too much to the front ; and whilst indi- 

 vidual plants are fully described, and very complete and 

 minute accounts are given of the development of their 

 \ arious organs, one loses, to some extent, the feeling of 

 a wide synthetic grasp of the plants as a whole. It is 

 true, however, that this is atoned for by the suggestive 

 summaries and discussions on phylogeny at the end of 

 the chapters. 



Many readers will probably wish that Prof. Campbell 

 liad devoted a little more space to a comparative treat- 

 ment of the external forms, and had also given some 

 account of the numerous biological adaptations which 

 are so abundantly exhibited by many ferns and mosses ; 

 and we cannot help feeling that this would have been 

 acceptable, even if it had necessitated the sacrifice of 

 space now devoted to details of development. 



The only point about the book which really strikes 

 us unfavourably is the scanty recognition accorded to 

 ''aUeontology. It is just amongst the vascular crypto- 



iins that the pakeophytologist is at his best, and we 

 . cnture to express the hope that in future editions this 

 most important branch of the subject may be far more 

 fully treated. 



If we have seemed to have indulged in a few adverse 

 criticisms, this has not been done with any hostile inten- 

 NO. 1366, VOL. 53] 



tion, but merely by way of attempting to point out how, 

 in our judgment, a really fine work may perhaps be im- 

 proved. Enough, however, has, at any rate, been said 

 to show that Prof. Campbell has rendered a most im- 

 portant contribution to the literature of botany ; and we 

 cannot, finally, suppress an expression of gratification 

 that it should have appeared in the English language. 



OUR BOOK SHELF. 



A Laboratory Manual of Organic Chemistry. By Dr. 



Lassar-Cohn. Translated by Alexander Smith, B.Sc, 



Ph.D. Pp. vii -I- 403. (London : Macmillan and Co., 



1895.) 

 It will be readily understood in these days of rapid 

 research that the appearance of a compendium of the 

 latest reagents, processes and apparatus, intended to 

 curtail the labour of the laboratory, would prove accept- 

 able to organic chemists, and it is not surprising that the 

 second German edition of this work should have appeared 

 within a brief period. Its success in Germany may be 

 taken as a guarantee that the English translation will be 

 well received. The original will already have found its 

 way, without doubt, into some of our laboratories. There 

 are many useful laboratory methods scattered through 

 the literature, which are frequently difficult to lay one's 

 hand on at once. The present volume, which has been 

 compiled with much discrimination, gives an account of 

 all the important laboratory operations used in organic 

 research, carefully described and illustrated. In these 

 descriptions either the original account is reproduced, or 

 a sufficiently detailed description is supplied by the author, 

 so that a final appeal to the reference may generally be 

 dispensed with — an important point, since herein lies the 

 essence of the book's utility. The less important methods 

 are briefly mentioned with a reference to the original 

 paper. To try and strike a mean between these two 

 extremes is obviously useless, and occasionally the author 

 falls into this error. For example, under "aluminium 

 chloride " (p. 105), it is stated that this substance is pre- 

 pared from aluminium and chlorine. Then follows a 

 fairly long account of a method by Gattermann, from 

 aluminium and hydrochloric acid. The description is 

 unaccompanied by any diagram, and is so incomplete 

 that I am confident that any one who attempted to prepare 

 it for the first time from this description would fail. In 

 such a case the author would render a greater service by 

 simply giving the reference. 



The book does not aim at teaching the principles of 

 organic chemistry, and it is perhaps not fair to find fault 

 with some of the expressions and definitions used, which 

 are apart from its main purpose. One brief reference 

 may be permitted. 



Chapter xii. (p. 10) contains a general account of 

 " condensation." The writer has never met with any 

 good definition of this term, and it is perhaps, as Gmelin 

 said of the relation of organic to inorganic chemistry, 

 more easily felt than defined ; but surely we have here 

 a needless confusion of ideas or, at least, of language. 

 In the first paragraph we read : " By condensation we 

 mean the formation of a substance from two others with 

 loss of water, alcohol, hydrochloric acid, ammonia, or a 

 halogen from both components." That the two others are 

 not necessarily organic substances we learn from the next 

 paragraph, where an example of condensation is given in 

 the case of hydroxylamine and an aldehyde. Consequently 

 we may include in this term the formation of ethereal 

 salts, nitro-compounds, sulphonic acids, &c. Further 

 down we read : " We include under this heading also the 

 phenomenon of internal condensation, in which a body 

 loses water and forms a new substance." Is the formation 

 of ethylene from alcohol condensation f In the next para- 



