VA TURE 



457 



THURSDAY, MARCH 19, 1896. 



THE PHYSIOLOGY OF THE EXCITABLE 



TISSUES. 



Elektro-physiologie. Von W. Biedermann, Professor 



der Physiologic in Jena. Zweite Abtheilung. Mit 285 



Abbildungen. Pp. 441 to 857. (Jena : Fischer, 1895.) 



THE second volume of Prof. Biedermann's work, now 

 before us, fully maintains the reputation of its 

 author, and is, if anything, still more interesting than the 

 preceding volume dealing with muscle. 



This additional interest, though due in some measure 

 to the subject-matter, embracing, as this does, the funda- 

 mental excitatory phenomena of nerve, the functional 

 activity of electrical organs of fishes, and the electro- 

 motive phenomena of plant and glandular structures, is 

 aroused and maintained by the evident drift of the writer 

 towards a full expression of those views which he is 

 known to share with Prof Hering, and which the present 

 volume affords him an opportunity of enunciating. 



Such an exposition of the mental attitude of the 

 present occupant of the Leipzig chair of Physiology (Prof. 

 Hering), in regard to the play of those vital processes 

 whose physical manifestations are the objects of the 

 physiologist's investigation, is of the highest importance, 

 since it is well known that the influence of this conception 

 upon the physiological science of to-day is as great as 

 was that of Hering's distinguished predecessor, Prof. 

 Ludwig, on the science of a few years back. 



The clear account here given of the two aspects of 

 physiological change, association and dissociation, and 

 their relation to the physical aspects of vital phenomena, 

 is further increased in value by its setting. Placed at 

 the end of the chapters on nerve, in that devoted to the 

 theoretic views as to the electromotive phenomena of 

 this structure, the author, adopting the historical method, 

 leads up to Hering's theory through the earlier molecular 

 theory of Du Bois Reymond and the very differently 

 conceived theory of Pfluger, both of which rest upon a 

 mechanical scheme as their basis, and the author then 

 shows to what an extent the views of these two writers 

 paved the way for that which he proceeds to present in 

 Hering's words. Perhaps no more striking testimony to 

 the universal character of the present acceptance of this 

 latter view, could have been brought forward than the 

 theory of Bernstein, the exposition of which follows that 

 of Hering, since it brings into prominence the modifica- 

 tions in Hering's sense, which even such a staunch 

 adherent of the molecular theory as the Hall^ Professor 

 has felt it necessary to elaborate. 



The position here taken up by Prof. Biedermann is 

 held by him to be the only one at present capable of 

 embracing within its scope all the various phases of 

 excitatory change, and its tenability is supported by an 

 array of fundamental reaction phenomena, many of which 

 have been ascertained by his own researches. 



An interest of a very special kind is thus given to the 

 description of the characters of th2 excitatory efitects in 

 nerves. 



Such, for instance, is the e.xperimcntal comparison 

 between the circumstances which condition the excitatory 

 NO. 1377, VOL. 53] 



effects produced on the opening of a galvanic current 

 which has been led through a nerve. The initial,, 

 suddenly-developed, and comparatively short-lived mus- 

 cular response to the opening nerve excitation (opening 

 twitch) is shown to be essentially dependent upon a 

 preceding constrained state of greater inexcitability 

 (theoretically, association), and, as it is brought about by 

 the removal of the constraining agent (the galvanic 

 current), may be considered as a dissociation rebound 

 from this condition. It is contrasted with a second more 

 slowly developed and more lasting excitation, evoking in 

 the muscle an opening tetanus, the essential productive 

 factor of which is a preceding state of greater excitability 

 {dissociation), a latent excitation now rendered kinetic in 

 consequence of the slight additional dissociation effected 

 by such a rebound. The play of different conditions 

 upon the two effects is brought into prominence by the 

 description of some most striking experiments, in which, 

 one is affected to the exclusion of the other by means of 

 a special environment. 



Such, again, is the description of the response evoked 

 by nerve excitation in the muscles which respectively 

 open and close the claw of the crayfish, a response which 

 may be either the well-known contraction or a less- 

 familiar muscular relaxation (inhibition) ; experimental 

 results which probably find their parallel in the well- 

 known effects produced in cardiac muscle by e.xcitation 

 of the vagus nerve. 



The excitatory electromotive changes localised to the 

 neighbourhood of the poles when a galvanic current 

 commences or ceases to flow through a nerve, the dis- 

 tinction between the vital reaction phenomena and the 

 physical polarisation phenomena in special relation to the 

 production of the extrapolar electrotonic currents, the 

 specific reactions of etherised and of cooled nerves, the 

 effect of different saline substances upon these reactions,, 

 are but a few of the many pertinent examples brought 

 forward, the concise, clear statement of which renders 

 the present volume such a valuable contribution to 

 physiology. 



It is perhaps to be regretted that the arrangement of 

 subject-matter adopted by the author has involved the 

 necessity of grouping such a large number of phenomena 

 under the heading " Die elektrische Erregung der 

 Nerven," with the result that this enormous chapter is 

 100 pages long. We venture to think that this portion 

 might with advantage have been split into several sub- 

 sidiary sections. A very large part of the present know- 

 ledge of nerve activity has been obtained by the use of 

 electrical methods of excitation, and a vast amount of 

 work has, in consequence, been carried out upon this 

 aspect of the question. It is, therefore, an almost her- 

 culean task to set forth in unbroken continuity all the 

 phenomena which fall within the scope of this title, and 

 to do so without running the risk of making such 

 narration wearisome to the reader, and annoying to the 

 reference student who seeks information on one particular 

 group of such phencmena. Prof. Biedermann has run 

 this risk, and it cannot honestly be said that he has suc- 

 ceeded in avoiding the danger. As it stands at present,, 

 this chapter, although teeming with interesting details, 

 because of this very fecundity, may not impossibly cause 

 the reader to agree, during its perusal, with the remark 



X 



