( 49 ) 



The above experiment was made with a dead muscle, to avoid 

 as much as possible all variable factors of the living object. These 

 come into operation, as appeared from experiments, in which first 

 a curve was produced by observations of a living muscle, and the 

 next day a second curve could be formed from observations of the now 

 dead muscle, which under a glass cover with saturated vapour of water 

 and thymol-vapour w r as preserved resp. from desiccating and rotting. 

 The values denoted by the curve are averages got from at least five 

 observations each time, which did not materially differ from each other. 



io c 



X.Q° 



3o° 



V0° 50' 



Fig. 2. 



6o ö 



jo' do 



Hardness with regard to different heights of falling by a muscle 



in its dead and living situation. 



— — = living muscle. = dead muscle. 



The ordinate gives the number of audible taps and the abscis the 

 initial height of falling in degrees. 



In different ways the hardness of a muscle can be made to undergo 

 changes, which are either permanent, or which exist long enough 

 for the determining investigation : 



1. by making a galvanic current pass through a muscle; 



2. by abundant moistening with equimolecular salt-solutions; 



3. by faradaic excitement, either direct or indirect, so that the 

 muscle is in tetanus; 



4. by heating, resp. cooling. 



An example of the two first mentioned manners was given before ; 

 one of the two other manners is as follows : a muscle is by indirect 

 excitement with a faradaic current alternately brought to tetanus. 

 At corresponding moments the determinations of hardness take place. 



Proceedings Royal Acad. Amsterdam. Vol. XI. 



