782 



SCIENCE. 



[N. S. Vol. XXIII. No. 594. 



greatly to the interest of the work to have had 

 a discussion of the climatic conditions based 

 on the paleobotanical and other evidence at 

 the command of the author. 



While largely a matter of speculation, it 

 •would seem that the question of an Antarctic 

 continent rather than the more restricted 

 Gondwanaland in lower latitudes might have 

 been considered with profit, although such a 

 discussion might possibly be out of place in a 

 publication of this sort, at any rate, its omis- 

 sion can in no wise be urged as a criticism of 

 this admirable piece of work. 



In the matter of nomenclature Arber is 

 cautious, one might say conservative, through- 

 out, and scant space is devoted to those species 

 founded upon fragmentary and indefinite im- 

 pressions. This 'lumping' process does not 

 seem to be a defect, as many believe it to be 

 in some of the preceding volumes of the 

 British Museum Catalogues, although un- 

 doubtedly the actual abundance of species in 

 nature is thereby probably underestimated. 



In the genus Glossopieris the great varia- 

 bility of size and shape in the same species is 

 emphasized, attention being called to the 

 danger of founding species upon such charac- 

 ters as the thickness or persistence of the 

 midrib, the obtuse or acute apex, or differ- 

 ences in the angles of divergence of the sec- 

 ondary veins, all characters more or less 

 closely correlated with the size and shape of 

 variable fronds. The only characters which 

 seem reasonably safe in systematic work, until 

 internal structures are known, are the average 

 shape of the areoles and the openness or close- 

 ness of the secondary veins. In a revision 

 from this viewpoint, confessedly artificial, the 

 author reduces the large number of species of 

 Feistmantel and others, to thirteen forms. 



Considerable space is devoted to what little 

 is known of the fructifications of this genus, 

 and many other items of botanical interest are 

 found throughout the work. Mr. Arber is to 

 be congratulated for the way in which he has 

 completed a difficult task, and paleobotanists 

 owe him a debt of gratitude for the thorough 

 way in which he has organized and systema- 

 tized the literature and nomenclature of this 

 most interesting and heretofore least known 



flora. Some ninety-two species besides a 

 number of indefinite remains are catalogued. 

 The illustrations are ample and well executed, 

 there being 8 plates and 51 text figures in 

 addition to a map showing the supposed land 

 areas of the Permo-Carboniferous. The sys- 

 tematic portion is preceded by a discussion of 

 the botanical affinities of the flora, its distri- 

 bution in space, its age and distribution in 

 time, including specific and geologic tables of 

 distribution and correlation, a historical 

 sketch and a history of the collection. The 

 bibliography is complete and the work taken 

 as a whole merits nothing but the warmest 

 praise. Edward W. Berry. 



Mabtland Geological Sxjbvet, 

 Baltimoee, Md. 



Chemie der alicyJclischen Verbindungen. Von 

 Ossian Asohan, a. o. Professor an der 

 TJniversitat Helsingfors. Braunschweig, 

 Fr. Vieweg und Sohn. 1905. Pp. xlvi + 

 1164. 



The alicyclic or polymethylene compounds, 

 sometimes also called hexahydrobenzene de- 

 rivatives, have, up to the present time, re- 

 ceived rather stepmotherly treatment from 

 text-book writers. Some of the substances 

 have been described in connection with the 

 aliphatic compounds, while others have been 

 placed in the aromatic section. In short, like 

 most other transition forms, their classifica- 

 tion was troublesome and, except in so far as 

 they were of use in connecting the two great 

 families of organic compounds, they were kept 

 as much in the background as possible. To 

 some extent this was unavoidable; it is only 

 in more recent years that it has been possible 

 to prepare well-defined, crystalline derivatives, 

 the study of which could lead to valid conclu- 

 sions regarding the constitution of the parent 

 substances; indeed, the preparation, in a state 

 of purity, of many of the latter is attended 

 often with very great experimental difficulty, 

 and yet a fairly large number of the alicyclic 

 compounds which occur in nature, such as 

 camphor and various terpenes, are of consid- 

 erable technical importance. 



Professor Aschan's book marks the termina- 

 tion of this state of things, and already one of 



