December 8, 1892] 



NATURE 



129 



Opening with an historical introduction which deals 

 briefly with the development of the art from classical 

 times down to the present day, the author proceeds to 

 indicate the general scope of his own investigations, and 

 to describe the methods of experiment which he employed. 

 The immediate problems which he sets himself to solve 

 are contained in two questions which occur on an early 

 page of his book, namely — Is it possible to remove parts 

 of a given plant and transplant them to any other position 

 in the same or a similar plant ? And upon this question 

 follows the second —What is the nature of the reaction 

 which occurs between the newly-introduced portion and 

 the surrounding tissues ? 



But although these form the proximate questions which 

 are to be answered by means of a large number of well- 

 conducted experiments, it soon becomes clear to the 

 reader that the chief interest which attaches to the results 

 obtained depends on their application to the theory of 

 polarity of cells and tissues which Prof. Vochting has al- 

 ready put forward elsewhere. 



The plants chiefly (but by no means exclusively) used in 

 the investigations wevG Beta vulgaris ?\.nd Cydonia japo- 

 nica. The former is of a fleshy and succulent character, 

 whilst the latter is a woody plant which happens to be 

 specially adapted to the various operations of grafting, 

 and, as it is a perennial, it admits of the results of the 

 experiments being watched for a considerable period of 

 time. Prof. Vochting distinguishes in every part of the 

 plant between a "shoot-pole" and a "root-pole,'' and 

 these he considers to be always present, however small 

 the plant member, or piece of excised tissue, may be. 

 The polarity manifests itself at the free surf ices, much as 

 the effects of the magnetism of a bar magnet are visible 

 at its ends ; and moreover, just as the pieces of a broken 

 magnet are themselves duly polarized, so also fragments 

 of tissue exhibit relations of polarity identical with those 

 characteristic of the organism from which they were 

 derived 



The first precaution necessary to secure success in 

 grafting is to respect the existences of the shoot- and root- 

 poles, and to insert the scion in such a way as to bring 

 its poles into due correspondence with those of the stock. 

 Acting upon this principle it is found that, generally 

 speaking, any member may be grafted on any other 

 member unless there is some special reason to the con- 

 trary, such as may be connected, for example, with nu- 

 trition or water-supply. The leaf of the beet will " take " 

 if grafted on a root, and vice versa, and it was also found 

 that it was possible, in the case of roots with diarch 

 bundles, to effect a union even when the xylem planes 

 in the two portions were made to cross each other at 

 right angles ; analogous results were also obtained with 

 leaves. Hence the author concludes that there is no 

 inherent fixity in the organization of plants which pre- 

 determines a definite sequence of the chief members of 

 which they are composed. 



Experiments were made with the object of determining 

 the mutual reactions between the stock and the scion, and 

 the conclusion arrived at is that beyond such changes as 

 may be referred to nutritional and similar causes, the 

 two remain unaltered, at least in so far as their specific 

 characters are concerned. Prof. Vochting criticises un- 

 favourably the various alleged cases ot the so-called 

 " graft-hybrids," and points out that even in one of the 

 best authenticated examples, that of Cytisus Adami^ all 

 attempts to produce the hybrid afresh have resulted in 

 failure. 



The most interesting part of the book is occupied with 

 the account of researches into the behaviour of trans- 

 planted portions of tissue, the direction of whose " po- 

 larity " does not coincide with that of the parts into which 

 they are introduced. When the inserted portion of tissue 

 is rotated on its longitudinal axis so that its own tangential 

 surfaces are applied to the radial ones of its new host, 



NO. 1206, VOL. 47] 



difficulties arise in the accomplishment of a complete 

 union, and these difficulties are further increased to a 

 maximum when the tissue is put in upside-down, so to 

 speak, that is with its own poles presented to similar 

 poles in the stock. A great number of experiments were 

 instituted to investigate these reactions, but space forbids 

 any attempt to do more than briefly summarize the most 

 important points. In the case of Cydonia japonica a 

 ring of rind was cut out of a twig and replaced in the 

 reversed direction. In many cases the twigs behaved as 

 if the tissue had not been restored at all, simply dying, 

 whilst in others a subsequent healing took place. This 

 healing was accompanied by a swelling at the upper 

 junction, together with the appearance of a ridge oftissu'; 

 which was formed along the longitudinal suture of the 

 ring from above downwards and was derived from the cam- 

 bium of the ring, and not by an ingrowth of callus from 

 the uninjured cortex of the twig, as might perhaps be sup- 

 posed. In this way connection between the interrupted 

 rind was re-established, and growth recommenced. But 

 both at the edges of the tissue-ridge, and also between it 

 and the original underlying xylem, the cell elements were 

 found to be disposed in a remarkable manner, forming 

 curved unions with the cells of the healthy tissues. 

 For the histological details the reader is referred to the 

 original treatise ; suffice it to say that Prof. Vochting be- 

 lieves that he has found in the appearances thus pre- 

 sented, additional evidence for the validity of his theory 

 of the polarized condition of living tissues. He conceives 

 of these polarities as properties which are the expression 

 of the innermost relationships existing between the con- 

 stituents of which cells are built up. He further regards 

 the polarity of any tissue as irreversible when once the 

 direction has been imparted to it, and he finds justifica- 

 tion for this view not only in the details of his own ex- 

 periments on grafting, but also in the results of investiga- 

 tions conducted by Kny and others, on the effects of 

 compelling parts of plants to grow in a reversed position. 

 After discussing some of the objections to his theory, 

 without, however, disposing of them all, the author con- 

 cludes by stating, with considerable reserve, some of the 

 wider applications of his theory in explaining geotropism 

 and other allied phenomena. 



The book certainly forms one of the most important of 

 the recent contributions to plant physiology, and the ex- 

 perimental details are well illustrated in the eleven plates 

 which accompany the text, whilst the diagrams in the body 

 of the work serve to render the author's theoretical views 

 more intelligible. J- B. F. 



NOTES. 



A GOLD MEDAL is to be presented to M. Pasteur on December 

 27, his seventieth birthday. 



On Monday Lord Durham laid the foundation stone of a new 

 wing of the College of Science, Newcastle, which, like the Col- 

 lege of Medicine in the same city, is a branch of the Durham 

 University. The College of Science was established at West- 

 gate-hill, Newcastle, in 1871. Lord Armstrong laid the foun- 

 dation stone of the present premises at Barras Bridge in 1887, 

 and in the following year the existing wing was opened by the 

 Marquis and Marchioness of Lorne. The success of the institu- 

 tion is strikingly indicated by the fact that the increase in the 

 number of students has rendered a new wing absolutely neces- 

 sary. 



Dr. Werner Siemens, the well-known electrical engineer, 

 died at Berlin on Tuesday. He was seventy-six years of age. 



Mr. W. H. Preece, F.R.S., has been appointed a member 

 of the Royal Commission on Electrical Communication with 

 Lighthouses, &c., in the place of Mr. Edward Graves, de- 

 ceased. 



