482 



SGIENGE. 



[N. S. Vol. V. No. 116. 



of contractions varying from minimal to maxi- 

 mal in amplitude, the latent period is observed 

 to become progressively shorter. The weaker 

 waves of submaximal contraction do not pass 

 through the full length of the muscle, and the 

 unexcited part of the tissue acts simply as an 

 elastic band whose tension must be increased to 

 a definite degree before visible shortening of 

 the whole muscle can take place. It can readily 

 be seen that the time lost through the extensi- 

 bility of the uncontracting part of a muscle fibre 

 largely accounts for the ' latent period of stimu- 

 lation.' The adjective ' Subliminal,' used by the 

 translator to express a stimulus too weak to 

 excite contraction, is not to be found in Webster. 



Errors of type and expression in the work are 

 not numerous ; but in the figures of tracings 

 representing the effect of rest on the curve of 

 muscular fatigue the increased height in the 

 contractions immediately following an interval 

 of rest is not represented. Also, on page 540, 

 the terms hilus and hilum are used indiffer- 

 ently. 



Certain views which are implied, rather than 

 expressed, should not be admitted without 

 specific inquiry. Thus, the author assumes a 

 likeness in kind between those summations of 

 stimuli, each stimulus by itself being ineffective, 

 which, on the one hand, produce tetanus in 

 certain slowly moving muscles, and, on the 

 other, cause refiex action from the spinal cord 

 when applied to a sensory surface (p. 119). 

 It is a satisfaction to find, at last, an author 

 who gives true value to current density as a 

 physiological stimulus rather than to current 

 intensity ; a current of given intensity has very 

 different stimulating powers according as it is 

 led to the tissues through broad or narrow 

 electrodes. To the younger student, the ex- 

 planation that physiological kathode, or point 

 of excitation by the electric current, is at the 

 place where the current leaves the irritable tis- 

 sue, will clear up many obscure results of ex- 

 periment. The author draws, perhaps, too 

 close an analogy between the polar excitation 

 effects shown by some protozoa on the passage 

 of a constant current through them and the ex- 

 citatory phenomena of muscle and nerve. There 

 is nowhere to be found a more complete discus- 

 sion of du Bois-Eeymond's law of the excitation 



of irritable tissues. The law asserts, in brief, 

 that it is not the absolute intensity of the stimu- 

 lus which determines its irritating value, but 

 fluctuation in intensity. Biedermann shows 

 that the prolonged contraction manifested by 

 muscle during the passage of a constant current 

 through it forms no true exception to the law. 

 He also calls attention to a needed amendment 

 to duBois-Reymond's law, in that " not merely 

 the local changes at the seat of excitation, but 

 still more the propagation of the excitatory 

 process, i. e. , the discharge of a wave of excita- 

 tion (contraction), are dependent upon the vari- 

 ations of current intensity, and the steepness of 

 the same, in the case of tissues in which con- 

 ductivity is adequately developed. The ' uni- 

 versal law of excitation ' refers, therefore, less 

 to the manner of the excitatory process, and 

 effectuation of the changes of the excitable 

 substance fundamental to it, at the seat of direct 

 excitation (physiological anode and kathode), 

 than to the conditions of the propagation of the 

 excitatory process by conduction" (p. 314). 



It is a disappointment to find that, as yet, 

 there is little light to be shed upon the relations 

 between the excitatory and contraction waves 

 of muscle. 



Much abtruse and technical literature would 

 have to be culled in order to reach the results 

 so ably summarized in the sections on electro- 

 motive action in muscle ; particularly satisfac- 

 tory are the pages devoted to the ' Positive 

 variation of the muscle current. ' 



It is a worthy reward for all the thought and 

 labor that for nearly fifty years have been 

 devoted to electro-physiology, to find that here 

 the facts are pointing to a physiological gener- 

 alization which was first conceived in another 

 field of the science. A decade ago Gaskell, as 

 the result of a masterly series of researches, 

 concluded that to each contractile tissue there 

 were supplied two forms of nerve fibre, a mo- 

 tor and an inhibitory branch, the former excit- 

 ing to functional activity and the latter bring- 

 ing the organ to' rest. As motor action, repre- 

 senting evolution of energy, is a result of chem- 

 ical disassimilation, so inhibition is coincident 

 with absorption of energy by a tissue and its 

 chemical change is one of assimilation. This 

 theory, arrived at by a study of the phenomena 



