222 



NATURE 



\yan. 9, 1890 



most valuable one — valuable because it embodies the 

 vi^hole of his numerous scattered writings on the group in 

 question. 



In making a selection of Dr. Gray's work for re- 

 publication, Prof. Sargent naturally did not choose de- 

 scriptive botany, though an index to the genera and 

 species described in a variety of more or less inaccessible 

 publications would be of the utmost service to botanists ; 

 for even under the most favourable conditions a long time 

 must elapse before the completion of the " Synoptical 

 Flora." 



The selection, " which was found difficult and em- 

 barrassing," is limited to reviews of works on botany and 

 related subjects, essays, and biographical sketches, and 

 it is on the whole, doubtless, as good a one as could have 

 been made. Gray wrote "more than eleven hundred 

 bibliographical notices and longer reviews," and, as space 

 for only fifty is found in a volume of 400 pages, it follows 

 that " it was necessary to exclude a number of papers 

 of nearly as great interest and value as those which are 

 chosen." 



Dr. Gray's method, if I may so term it, of reviewing 

 the productions of his contemporaries was of such an 

 instructive, temperate, and impartially critical character 

 that these reviews have a permanent value. On reading 

 some of them again, one is more than ever impressed 

 with the fact that he made himself thoroughly acquainted 

 with the works he criticized, and that he well fulfilled his 

 duty alike to the public and the author. He did not hesi- 

 tate to point out what he regarded as defects in the 

 writings of his most intimate friends ; but he was more 

 careful to give an analysis of the contents of a book, with 

 his own views thereon, than to condemn it on its faults or 

 weak points. 



These reviews cover a wide field, as well as a long 

 period, and still remain profitable and interesting reading. 

 The selection is too limited to be a history of botany 

 during the last half-century, but it is sufficiently com- 

 prehensive to give an idea of the most notable events. 

 It is true that the essays on the Darwinian theory are not 

 here reproduced, as they had already been republished by 

 their author. 



The first volume, which is devoted to reviews, com- 

 mences with a detailed notice of the second edition of 

 Lindley's " Natural System of Botany " and ends with 

 Ball's " Flora of the Peruvian Andes," reminding us of 

 our most recent loss in the very small circle of private 

 gentlemen who may be said to have studied botany 

 successfully. 



Early among the reviews is that of Endlicher's '• Genera 

 Plantarum," a work published at intervals between 1836 

 and 1840 ; and, almost at the end, a short article on the 

 completion of Bentham and Hooker's " Genera Plan- 

 tarum," 1862-83. In the latter we find a comparison of 

 the number of genera admitted in various works of the 

 same class, from the appearance of the fifst edition of 

 Linnaeus's "Genera Plantarum," in 1737, down to 

 Bentham and Hooker, and remarks on the ideas of 

 generic limits entertained by the different authors, and on 

 the relative quality of their work. 



Interspersed between these are notices of such widely 

 different subjects as De Candolle's " Prodromus " ; von 

 Mohl's "Vegetable Cell" ; Boussingault, " On the Influ- 



ence of Nitrogen " ; Bentham's " Hand-book of the British 

 Flora"; De Candolle's "GeographieBotanique"; Hooker's 

 " Distribution of Arctic Plants " ; Ruskin's " Proserpina" ; 

 Darwin's " Insectivorous Plants " ; and Wallace's " Epping 

 Forest." 



Among the fourteen " Essays " in the second volume^ 

 those on the longevity of trees, the flora of Japan, 

 Sequoia, and forest geography and archaeology, may be 

 named as specially interesting. 



The biographical sketches are thirty-eight in number, 

 ranging from Brown and Humboldt to Bentham and 

 Boissier. As only some two hundred pages are devoted 

 to them, these sketches are, many of them, necessarily 

 very brief; but, as Gray had a personal knowledge of 

 most of the men of whom he wrote, they contain original 

 and interesting observations and facts not to be found 

 elsewhere. And all who knew Dr. Gray will enjoy 

 I'eading again his opinion of other men and their works. 



W. BOTTING HEMSLEY. 



MANURES AND THEIR USES. 



Manures and their Uses. By Dr. A. B. Griffiths. (London; 

 George Bell and Sons, 1889.) 



THIS is a hand-book for farmers and students, and 

 may be described as a smaller and less ambitious 

 successor to the treatise on manures, by the same author, 

 reviewed some months ago in Nature. The principal 

 value of this latter work consists in the direct information 

 it contains as to sources of phosphatic, potassic, and nitro- 

 genous manures, including guanos, in all parts of the world. 

 The analyses, localities, amounts imported, and values, are 

 all interesting facts for farmers, and this little book may 

 well take its place in an agricultural library as supplying 

 knowledge which otherwise might need research through 

 many scattered sources of information. When, however, 

 we consider the book as a means for imparting sound 

 views on agricultural principles, we must advise caution 

 on the part of the reader. Dr. Griffiths is one of those 

 teachers who are infected with an inordinate affection for 

 chemical manures. He believes, with M. Ville, that " the 

 farmer who uses nothing but farmyard manure exhausts 

 his land," Now, a man who starts with such an obvious 

 fallacy can scarcely get into the right path. This doc- 

 trine is contrary to science and practice ; and until Dr. 

 Griffiths relinquishes it he cannot hope to enjoy the con- 

 fidence of any farmer. We venture to put the matter in 

 two or three positions from which it can be clearly viewed. 

 Dr. Griffiths says, " This [farmyard] manure is erroneously 

 supposed to contain a// the necessary plant-foods required 

 for the growth of crops." Erroneously ! why, farmyard 

 manure at least must contain all the constituents of straw, 

 for it is largely made of straw. Similarly, it must contain 

 the elements of turnips and root crops, when it is com- 

 posed of them in no small proportion. Also it must 

 contain the constituents of corn, because all meals and 

 cakes which are consumed by cattle, and all hay, which 

 is also consumed by cattle, contain the constituents of 

 corn in the form of nitrogen, phosphorus, sulphur, potash, 

 lime, magnesia, &c. Whether looked at chemically or 

 approached through pure reasoning, it is clear that farm- 



