134 



NATURE 



{Dec, 12, 187S 



Jodrell Laboratory at Kew, ara Dr. Burdon Sandersoi's 

 investigations on the exceptional property possessed by the leaves 

 and other organs of some plants which exhibit definite move- 

 ments in response to mechanical, chemical, or electric stimuli. 

 In 1873 this physiologist showed us in our meeting-room that the 

 closing of the lamina: of the leaf of Dioncca is preceded by a 

 preliminary state of excitement, and is attended with a change 

 in the electric conditions of the leaf; and this so closely 

 resembled the change which attends the excitation of the excit- 

 able tissues of animals that he did not hesitate to identify the 

 two phenomena. 



This remarkable discovery" immediately directed the attention 

 of two German observers to the electromotive properties of 

 plants, one. Dr. Kunkel, in the laboratory of Prof. Sachs ; the 

 other. Prof. Munk, in that of the University of Berlin. 



Prof. Munk, whose researches are of much the '^greater scope 

 and importance, took as his point of departure Dr. Burdon 

 Sanderson's discovery. The leading conclusion to which he 

 arrived was that in Dicit^a each of the oblong cells of the paren- 

 chyma is endowed with electromotive properties which correspond 

 with those of the " muscle-cylinder " of animals; with this ex- 

 ception, that whereas in the muscle-cylinder the ends are nega- 

 tive to the central zone, in the vegetable cell they are positive ; 

 and he endeavours to prove that according to this theory all the 

 complicated electromotive phenomena which had been observed 

 could be shown to be attributable to the peculiar arrangement of 

 the leaf-cell^. 



During the last two summers Dr. Burdon Sanderson has been 

 engaged in endeavouring to discover the true relations which 

 subsist between the electrical disturbance followed by the 

 shutting of the leaf-valves of Diona^a and the latent change of 

 protoplasm which precedes this operation. He has found that 

 though the mechanism of the change of form of the excitable 

 parenchyma which causes the contraction is entirely different 

 from that of muscular contraction, yet that the correspondence 

 between the exciting process in the animal tissues and what re- 

 presents this in plant tissues appears to be more complete the 

 more carefully the comparison is made ; and that whether the 

 stimulus be mechanical, thermal, or electrical, its 'effects corre- 

 spond in each case. Again, the excitation is propagated from 

 the point of excitation to distant points in the order of their 

 remoteness, and the degree to which the structure is excited 

 depends upon its temperature. Notwithstanding, however, the 

 striking analogies between the electrical properties of the cells 

 oi Dioncca and of muscle-cylinders, Dr. Burdon Sanderson is 

 wholly unable to admit with Prof. Munk that these structm*es 

 are in this respect comparable. 



In morphological botany attention has been especially directed 

 of late to the complete life-history of the lower order of ci^pto- 

 gams, since this is seen to be more and more an indispensable 

 preliminary to any attempt at their correct classification. 



The remarkable theoiy of Schwendener, now ten years old, 

 astonished botanists by boldly sweeping away the claims to auto- 

 nomous recognition of a whole group of highly characteristic 

 organisms — the lichens — and by affirming that these consist of 

 ascomycetal fungi united in a commensal existence with alga?. 

 The controversial literature and renewed investigations which 

 this theory has given rise to is now very con'^iderable. But the 

 advocates of the Schwendenerian view have gradually won their 

 ground, and the success which has attended the experiments of 

 Stahl in taking up the challenge of Schwendener's opponents, 

 and manufacturing such lichens as Endocarpon and Thelidium, 

 by the juxtaposition of the appropriate algse and fungi, may 

 almost be regarded as deciding the question. Sachs, in the last 

 edition of his " Lehrbuch," has carried out completely the prin- 

 ciple of classification of alga?, first suggested by Cohn, and has 

 proposed one for the remaining thallophytes, which disregards 

 their division into fungi and alga?. He looks upon the former 

 as standing in the same relation to the latter as the so-called 

 saprophytes {e.g. Neotiid) do to ordinary green flowering-plants. 



This view has especial interest with regard to the minute 

 organisms known as Bacteria, a knowledge of the life-history of 

 which is of the greatest importance, having regard to the changes 

 which they effect in all lifeless and, probably, in all living 

 matter prone to decomposition. This affords a morphological 

 argument (as far as it goes) against the doctrine of spontaneous 

 generation, since it seems extremely probable that just as yeast 

 may be a degraded form of some higher fungus. Bacteria may 

 be degraded allies of the Oscillatorice, which have adopted a 

 purely saprophytal mode of existence. 



Your Proceedings for the present year contain several im- 

 portant contributions to our knowledge of the lowest forms of 

 life. The Rev. W. H. Dallinger, continuing those researches 

 which his skill in using the highest microscopic powers and his 

 ingenuity in devising experimental methods have rendered so 

 fraitful, has adduced evidence which seems to leave no doubt 

 that the spores or germs of the monad which he has described 

 differ in a remarkable manner from the young or adult monads 

 in their power of resisting heated fluids. The young and adult 

 monads, in fact, were always killed by five minutes' exposure to 

 a temperature of 142° F. (61° C), while the spores germinated 

 after being subjected to a temperature of 10° above the boiling- 

 point of water (222° F.). 



Two years ago, Cohn and Koch observed the development of 

 spores within the rods of Bacillus subtilis and B. anthracis. 

 These observe tions have been confirmed, with important addi. 

 tions, in these two species by Mr. Ewart, and have been extended 

 to the Bacillus of the infectious pneumo-enteritis of the pig, by 

 Dr. Klein ; and to Spirillum by Messrs. Geddes and Ewart ; and 

 thus a very important step has been made towards the completion 

 of our knowledge of the life-history of these minute but im- 

 portant organisms. Dr. Klein has shown that the infectious 

 pneumo-enteritis, or typhoid fever of the pig, is, like splenis 

 fever, due to a Bacillus. Having succeeded in cultivating this 

 Bacillus in such a manner as to raise crops free from all other 

 organisms. Dr. Klein inoculated healthy pigs with the fluid 

 containing the Bacilli, and found that the disease in due time 

 arose and followed its ordinary course. It is now, therefore^- 

 distinctly proved that two diseises of the higher animals, namely,, 

 "splenic fever" and "infectious pneumo-enteritis," are gene- 

 rated by a contagium viviitn. 



Finally, Messrs. Downes and Blunt have commenced an inquiry 

 into the influence of light upon Bacteria and other Fungi, \\ hich 

 promises to yield results of great interest, the general tendency 

 of these investigations leaning towards the conclusion that 

 exposure to strong solar light checks and even arrests the 

 development of such organisms. 



The practical utility of investigations relating to Bacillus 

 organisms as affording to the pathologist a valuable means of 

 associating by community of origin various diseases of apparently 

 different character, is exemplified in the " Lcodiana fever," 

 which has been so fatal to horses in the East. The dried blood 

 of horses that had died of this disea-e in India has been recently 

 sent to the Brown Institution, and there afforded seed from 

 which a crop of Bacillus anthracis has been grown, which justi- 

 fied its distant pathological origin by reproducing the disease ia 

 other animals. Other equally interesting experiments have been 

 made at the same Institution, showing that the "grains" which 

 are so largely used as food for cattle, afford a soil which is 

 peculiarly favourable for the development and growth of the 

 spore filaments of Bacillus ; and that by such "grains" when 

 inspected, the anthrax fever can be produced at will, under con- 

 ditions so simple, that they must often arise accidentally. The 

 bearing of this fact on a recent instance in which anthrax 

 suddenly broke out in a previously uninfected district, destroying 

 a large number of animals, all of which had been fed with 

 grains obtained from a particular brewery, need scarcely be 

 indicated. 



In systematic botany, which, in a nation like ours, that is evo- 

 extending its dominions and exploring unknown regions ot the 

 globe, must always absorb a large share of the energies of its 

 phytologists, I can but allude to two works of great magnitude 

 and importance. 



Of these the first is the "Flora Australiensis " of Bentham, 

 completed only a year ago ; a work which has well been called 

 unique in botanical literature, whether for the vast area whose 

 vegetation it embraces (the largest hitherto successfully dealt 

 with), or for the masterly manner in which the details of the 

 structure and affinities of upwards of 8,coo species have been 

 elaborated ; its value in reference to all future researches re- 

 garding the geographical distribution of plants, the southern 

 hemisphere, and the evolution therein of generic and specifis 

 types, cannot be over-estimated. 



The other great work is the "Flora Braziliensis," commenced 

 by our late foreign Fellow, von Martins, and now ably carried on 

 by-Eichler, of Berlin, assisted by coadjutors (amongst whom are 

 most of our leading systematists) under the liberal auspices of 

 His Majesty the Emperor of Brazil. When completed, this 

 gigantic undertaking will have embraced, in a systematic form„ 

 the ve -fetation of the richest botanical region of the globe. 



