THE GRAPHIC METHOD 77 



III 



THE GRAPHIC METHOD 



THE studies next to be undertaken make use of 

 the change of form of the contracting muscle as 

 a partial index to the transformation of energy 

 in the tissue. A permanent record is desirable. 

 Further, the changes in the dimensions of the 

 muscle are so small that it is necessary to have 

 the graphic record enlarged, rather than of actual 

 size. To satisfy these conditions, the muscle is 

 attached near the fulcrum of a lever furnished 

 with a recording point. The surface for the 

 writing is usually glazed paper which has been 

 covered with a thin layer of soot by passing the 

 paper through the luminous part of a broad gas 

 flame. The paper is fastened (before smoking) 

 on a plate or on a drum which moves past the 

 writing point, almost parallel to it, and furnishes 

 thus a continuously fresh surface. 1 



1 The paper is cut wider and longer than the surface of the 

 drum. The extra width is to protect the bearings of the drum 

 from soot that might otherwise collect there in smoking the 



