SOME RECENT WORK UPON MUSCLE AND NERVE. 433 



fundamental vital characteristics. An excitable tissue 

 passes into a new active state on receipt of a stimulus ; the 

 activity thus evoked may persist for a considerable time or 

 may rapidly pass away, but in either case it is clear that a 

 complete return to the resting inactive condition may accom- 

 pany the subsidence of the state of activity. Such a restora- 

 tion of the tissue, the remaking of the particular molecular 

 combination which existed before the upset brought about 

 by the stimulus, is a striking feature of the activity of muscle 

 and particularly of nerve, hence these structures enable us 

 to examine the conditions which influence this phase of the 

 living cycle more completely than any others. The process 

 is of fundamental importance, since it is the antithesis of that 

 involved in the state of excitation, and both processes are 

 present in every living tissue. The stimulus acts upon one of 

 these, and it develops such preponderance that it masks the 

 opposite one. It is the peculiar merit of Prof. Biedermann's 

 book that this fundamental conception of living tissues so 

 strongly urged by his master, Hering, is kept before the 

 reader. 1 In such a tissue as muscle it is possible to ascertain 

 many essential characters of the state of restoration, and to 

 determine further how far the disappearance of the state of 

 activity is a necessary prelude for the reinstallation of the rest- 

 ing functional capacity. Will the tissue respond to a second 

 stimulus whilst the excitatory state evoked by the first is pre- 

 sent? It is well known that striated muscle will respond in 

 this way, so that even when a contraction due to one stimulus 

 is present it will contract again. Hence in this tissue a por- 

 tion only of the material whose change transforms the resting 

 into the contracted muscle is affected by the exciting agent ; 

 a second stimulus can initiate a further transformation in 

 another portion, and so on with a third and a fourth stimulus 

 until the total mechanical effect reaches four times that due 

 to the first response. 



On the other hand this trait is by no means universally 

 present, and even an allied structure like cardiac muscle 



1 The short account of Hering's theory of the functions of living matter, 

 published in 1888, has been translated into English by Miss VVelby, and 

 appeared in Brain, vol. lxxvii., p. 232 (1897). 



