Supplenicut to ''Nature" October ii, 1906 



points of discussion that a reader would naturally 

 suggrest arc considered by him exactly where the dis- 

 cussion is wanted, and it will be very easy to criticise 

 the work in the light of any further developments 

 w hich may arise at the hands of future investigators. 

 In extending the notion of entropy to radiation, he 

 Is working on the lines best calculated to advance 

 nur knowledge of thermodynamic phenomena. 

 When a system is in the course of undergoing an 

 irreversible transformation, the entropy at any instant 

 is a definite quantity, provided that at that instant 

 il is possible to conceive a reversible compensating 

 tr.msformation which would bring the system back 

 10 its initial state, and also that a definite line can 

 be drawn between the forms of energy that are to 

 be regarded as available and unavailable. In the 

 tase of radiation, it is important to push the notion 

 uf entropy as far as it w ill go. Only when this has 

 been done, and the results compared with those of 

 experiment, will it be ]K)ssible to say whether any 

 limitations exist in the statement that perpetual 

 motion of the second kind is impossible ; but the 

 vague and indefinite statements that have hitherto 

 hixn made regarding the [X)ssibility of such motion 

 have mostly been based on the consideration of pro- 

 cesses which, when performed cyclically, involve con- 

 siderable absorption of available energy, and the pro- 

 spects of obtaining perpetual availability from the 

 ether in ordinary cases of radiation are anything but 

 hopeful. G. H. Bryan. 



ELEMENTARY BOTANY. 

 (i) .4 Text-book of Botany. By John M. Coulter. 

 Pp. vii-(-365. (London: S. .\ppleton, 1906.) Price 

 55. net. 



(2) .4 first Course in Practical Botany. By G. F. 

 Scott Elliot. Pp. viii+344. (London: Blackie and 

 .Son, igo6.) Price 3s. 6d. 



(3) First Studies of Plant Life. By G. F. .Vtkinson. 

 Edited for use in English Schools by Miss E. M. 

 Wood. Pp. xiv-l-266. (Boston and London: Ginn 

 and Co., 1905.) Price 2s. 6d. 



(4) .4 Text-book of Botany. Part i. The .\natoniy of 

 Flowering Plants. By M. Yates. Pp. v-l-147. 

 (London : \\'hittaker and Co., 1906.) Price 2S. 6d. 

 net. 



(i) TNFLUENCED, it may be, by one's early train- 

 J- ing, it has always seemed most reasonable to 

 begin an elementary course of botany with morph- 

 ology, working in so soon as convenient the e.xplan- 

 aticn of form and structure in the light of purpose 

 served, an arrangement that is adopted by Prof. 

 Coulter in his text-book. 



The nature and modifications of leaf, stem, and root 

 -ire first considered, after which the student is directed 

 to the study of unicellular organisms, then to the 

 rxamination of types of increasing complexity selected 

 from the main taxonomic groups. The summaries of 

 these groups have been carefully prepared, the account 

 <if the fungi being specially comprehensive yet brief, 

 ■•"ollowing on the Bryophyta and ferns, a brief sketch 

 of the two generations of the horsetails and Ivcopods 

 NO. 1928, VOL. 74] 



leads up to the phanerogams. The lessons on flowers 

 and fruits are introduced with the angiosperms, and 

 ecology receives du(' n^cognition in the last few 

 chapters. 



As the book is liberally supplied with illustrations, 

 chosen with much forethought, it is observable that 

 Prof. Coulter has brought his extensive survey within 

 a remarkably small compass. The merit of the book 

 lies in the judicious selection of essential facts and 

 principles. The numerous references to economic 

 plants constitute a novel feature that is most notice- 

 able in the chapters on the classification of phanero- 

 gams. There would be little or no objection to offer 

 if the author made the most of their botanical 

 characters, but these are omitted, and only commercial 

 facts are given, occupying space that would be better 

 filled with botanical information. 



.'Vpart from this adverse criticism the book deserves 

 high commendation, and is admirably suited to its 

 purpose for use in secondary schools. 



(2) The practical course drawn up by Mr. Scott 

 Elliot presents a somewhat unusual arrangement, 

 inasmuch as the experiments are grouped on a morph- 

 ological basis; this has, it is true, some advantages, 

 but not sufficient to prefer it to the more usual 

 physiological disposition. 



A considerable amount of space is devoted to the 

 flower, as, in addition to one or two chapters, full 

 descriptions of two or more flowers are appended to 

 each day's work. The practice of giving students, 

 when time is available, a few flowers each day is 

 excellent, but it seems unnecessary to provide detailed 

 descriptions of all of them; further, the sequence— if 

 there is a sequence — is not suitable to beginners. 

 The theoretical discussions preceding, but not always 

 relevant to, the practical work are also long, and 

 curtail the space that is allotted to the actual experi- 

 ments. The experiments, numbering nearly a 

 hundred, are fairly representative, although the funda- 

 mental experiments of transpiration, respiration, and 

 osmosis are not so satisfactory or complete as one 

 could have wished. .\ sufficient amount of anatomical 

 work is included, and a useful bibliography is 

 appended referring the student to accounts of original 

 investigations. 



(3) Among the many elementary books dealing with 

 plant life, the studies by Prof. G. F. Atkinson, pub- 

 lished about four years ago, have a freshness and 

 vitality of their own. The numerous references to 

 American plants that are not known in this country 

 robbed the book of much of its value for use in schools 

 in the LInited Kingdom. This defect has been reme- 

 died by the introduction of British types, also, we 

 note, of British expressions. Excellent as were the 

 original drawings and photographs, the substitutes 

 prepared by Miss Wood and Dr. J. W. Ellis are quite 

 up to the same standard. 



(4) The smn'l volume prepared by Miss Yates is on 

 the lines of lae German " Repetitorium," and presents 

 a collection of morphological definitions and terms 

 with illustrations. In the course of thirteen chapters 

 the author collates the different organs of flowering 

 plants, their modifications, and the scientific terms 



