Apeil 18, 1902.] 



SCIENCE. 



623 



others, it has no peculiar charms for the au- 

 thor who refuses to be stampeded by tlie ap- 

 parently intelligent and purposive adaptations 

 of organisms to conditions never experienced 

 before or by the 'proportionate formation of 

 parts' in regenerating embryos and adults. 

 Such phenomena, he thinks, "may be entirely 

 beyond the scope of legitimate explanation, 

 just as are many physical and chemical phe- 

 nomena themselves, even those of the simplest 

 sort. * * * Even in the physical sciences it 

 would not be diificult to establish a vitalistic 

 principle, or whatever else it might be called, 

 if we choose to take into account such prop- 

 erties as the affinities of atoms and molecules, 

 etc. * * * For my part I see no grounds for 

 accepting a vitalistic principle that is not a 

 physico-causal one, but perhaps a different one 

 from any known at present to chemistry and 

 physics." 



Finally, if the adaptations shown in regen- 

 eration cannot be explained by natural selec- 

 tion are they to be explained by some teleo- 

 logical principle ? To this question the author 

 attempts no direct answer. It is pointed out 

 that not all forms of regeneration are adap- 

 tive, i. e., useful, and that 'unless we suppose 

 that some external agent, acting as we do our- 

 selves, directs the formative processes in ani- 

 mals and plants, we are not justified in extend- 

 ing our experience as directive agents to the 

 construction of the organic world.' 



These brief extracts do not do justice to the 

 author's argument, but they serve to show his 

 general position on these important questions. 

 The book will undoubtedly take a prominent 

 place among the standard biological works of 

 the world. 



E. G. C. 



Die Parngattung Niphoholus. By Professor 

 GiESENHAGEN. Jena, Gustav Fischer. 1901. 

 8vo. Pp. xii-t-223. Price, Mk. 5.50. 

 For a clean piece of monographic work the 

 ideal conditions are a genus of plants of 

 moderate size whose distribution is somewhat 

 circumscribed, and with sufficient adaptability 

 to environment to have induced striking struc- 

 tural characters among the species. Such a 

 condition is represented in the present genus. 



To monograph such a genus one needs, in addi- 

 tion to library and herbarium facilities, to be 

 possessed of a good knowledge of technique 

 and above all to know the plants in the field. 

 Such a knowledge of this genus Professor 

 Giesenhagen gained in his travels in Sumatra 

 and other portions of the East Indies and the 

 result is a clearly written monograph of the 

 fifty species of the genus. 



The genus forms a rather natural group 

 of ferns which has commonly been included 

 under the genus Polypodium, and is easily 

 recognized by the vestiture of star-like hairs 

 covering the laminae. The center of distri- 

 bution appears to be in India and South 

 China where nearly one half the species (21) 

 are found. Westward the genus extends to 

 Africa (two species), northward to Japan 

 (three species), eastward to Taiti ,(one 

 species), and southward to Australia (two 

 species). Endemic species are known from 

 most of the larger islands of this region, as 

 Bourbon (one), Ceylon (three), Sumatra 

 (one), Philippines (three), Java (two), 

 Celebes (two) and Borneo (one). One or two 

 species are well known in cultivation under 

 the name Polypodium Lingua. 



Sixty-five pages of the monograph are de- 

 voted to the morphology of the genus and the 

 details of stem and leaf anatomy are clearly 

 brought out, as are the modifications resulting 

 fi'om habitat and environment. __ This por- 

 tion of the work is illustrated by a well-se- 

 lected series of text figures illustrating struc- 

 tures comparatively, which is the only satis- 

 factory method for a work of this sort. The 

 descriptive portions are very clearly and fully 

 made, an entire paragraph being given to 

 anatomical details under each species — a valu- 

 able and noteworthy addition to ordinary tax- 

 onomic description. The English methods in 

 taxonomy are frequently commented upon 

 with no uncertain sound, being characterized 

 as a classification with 'hands and eies only' 

 (sic) by which they group together widely dif- 

 ferent species. The work of the English sys- 

 tematists who have hitherto recognized only 

 twenty-three species in this group, is sharply 

 contrasted with the careful work of Mettenius 

 and Kunze in Germany. The author, how- 



