NA TURE 



;6i 



THURSDAY, AUGUST i8, 1887. 



THE PHYSIOLOGY OF PLANTS. 

 Lectures on the Physiology of Plants. By Julius von 

 Sachs. Translated by H. Marshall Ward, M.A., 

 F.L.S. (Oxford : Clarendon Press, 1887.) 



IT is significant of the progress which the science of 

 botany has made in the last twelve years that the 

 accepted text-book of Sachs, which was published in 

 1873 as a single volume of 850 pages, is now represented 

 by three volumes with an aggregate of about 1900 pages. 

 The anatomical treatment in the original text-book was 

 condensed, and wanting in detail ; it is now replaced by 

 the comparative anatomy of De Bary. Book II. of the 

 text-book, which dealt with special morphology, has been 

 re-edited by Goebel as a separate work, a translation of 

 which has recently appeared (see Nature, vol. XXXV. p. 577). 

 The physiological portion of the original text-book, entirely 

 remodelled and re-written by its author, appeared in 

 Germany in the form of the " Vorlesungen uber Pflanzen- 

 physiologie," a translation of which is the book now under 

 review. In producing this as the last of the series of 

 three volumes above mentioned, the Clarendon Press has 

 completed an undertaking which must earn the heartiest 

 thanks of English students of botany. 



It is not improbable that the publication of this volume 

 will mark a stage in the history of the science in this 

 country. The period of dependence mainly on translated 

 text-books has now been of some duration, and it is not to 

 be expected or desired that translation should altogether 

 cease. Nevertheless it is unsatisfactory to receive the bulk 

 of our supply at second hand, and subject to those delays 

 which necessarily attend translation. It is to be confi- 

 dently hoped that a period of home production, which has 

 already begun, will now ensue, and thus demonstrate at 

 once the healthy growth of the science amongst us, and 

 the fact that there is still alive that skill of exposition 

 in which this country has not been deficient in the past. 



"Written in the lecture form, and in an easily-flowing 

 style, which the translator has successfully reproduced, 

 the book is aimed at, and should surely attract as well as 

 satisfy, " students and cultivated readers." The first five 

 lectures are devoted to organography, and writing as a 

 physiologist, with the express purpose of preparing the 

 way for a physiological treatment of the subject, the 

 author has adopted a method of " physiological organo- 

 graphy," protesting against that " purely formal morpho- 

 log^," which has been prevalent during the last thirty or 

 forty years, and which he complains of as having left the 

 physiological relations of organs entirely out of account. 

 In laying down his system of " physiological organo- 

 graphy," the author ranges all organs in five categories : 

 i) root, (2) shoot, (3) sporangia and spores, (4) arche- 

 jonia, (5) antheridia. It will be noted at once that the 

 arm shoot is used in a comprehensive sense including 

 eaf and stem where these are distinguishable. The shoot 

 IS a whole is thus co-ordinated with the root, a method 

 irhich commends itself physiologically as more suited to 

 Ihe time than the old distinction of stem, leaf, and root 

 s co-ordinate categories. Secondly, it will be observed 

 liiat the time-honoured attempt to recognize in the 

 Vol. XXXVI. — No. 929. 



sporangium the result of metamorphosis of some part 

 of the vegetative system, in fact, to define it as repre- 

 senting a metamorphosed leaf, pinna, ^c, is abandoned, 

 and Goebel's generalization that the sporangium is an 

 organ of independent nature is accepted. The author 

 then proceeds to apply his method of treatment to the 

 vegetative organs. Referring, by way of illustration, to 

 numerous plants, he distinguishes as typical forms of 

 root or shoot those which " present the essential peculiari- 

 ties in great perfection," he recognizes as rudimcntaiy 

 those parts of plants low in the scale, in which "the 

 organic differentiation generally is not so far advanced 

 as in the typical ones," and as reduced forms those in 

 which it may be assumed " that, in consequence of special 

 modes of life, more simply organized forms have again 

 arisen from those more highly organized." Lastly, he 

 designates as metamorphosed forms those " which have, 

 it is true, been derived later from the typical ones, but 

 which contribute to the greater perfection of the entire 

 organism," such as flowers, tendrils, &c. 



In the application of this system the rhizoids of mosses, 

 of fern prothalli, and liverworts, the organs of attachment 

 of various Algae, and even the mycelium of Fungi, are 

 designated " roots," while the term " shoot," including the 

 distinctive parts of stem and leaf, where these are dis- 

 tinguishable, is applied indiscriminately to the aerial parts 

 of vascular plants, mosses, Algae, and even to the fructifica- 

 tion of the Fungi. While accepting this method as throw- 

 ing a certain light on the various forms of plants, when 

 regarded from the physiological point of view, it cannot 

 be too strongly impressed upon us that it is in no sense a 

 substitute for the purely formal morphology. This is 

 clearly stated by the author himself, when he says (p. 72) 

 that his method " is by no means intended to exclude the 

 purely formal comparison as it has hitherto been con- 

 ducted under the name of morphology ; its effect on the 

 latter is only to be that of explaining and enlightening." 

 While reading these admirably-written lectures, some 

 whose bent is strongly physiological may think that 

 pure morphology has had its day, and is effete, while 

 the true and only point of view is the physiological ; but 

 it is not the author's object to teach this doctrine, and it 

 is to be regretted that, in order to avoid any uncertainty 

 of interpretation, a more distinct terminology was not 

 introduced. The author, who draws a clear distinction 

 between the morphological "member" and the physio- 

 logical "organ," might well have devised a system of 

 terms applicable exclusively in this physiological sense, 

 and so have both cleared the way for his own views and 

 have saved from risk of error those whose morphological 

 sense is dull. 



A concise exposition of the internal structure of the 

 plant follows, the cellular character of most plants being 

 contrasted with the structure of the Coeloblastae, which 

 Sachs has designated " non-cellular plants." This part, 

 though illustrated by many of the familiar figures from 

 the old text-book, has been entirely re-written in accord- 

 ance with more recent researches. It is not merely a 

 descriptive and comparative treatment ; the physiological 

 end is constantly kept in view, so that the first twelve 

 lectures may be regarded as preparatory to the more 

 purely physiological part which follows. After a short 

 explanation of the external conditions of vegetable life, 



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