A MUSCLE-PRISM AND A MAGNET. 



231 



south pole, and exhibits a regular decrease of the mag- 

 netic tensions from the poles to the centre. However 

 often the magnet is subdivided, each fragment is always 

 a complete magnet with two poles, and a regularly 

 decreasing tension. To explain this, it is assumed that 

 the whole magnet consists entirely of small particles 

 (molecules), each of which is a small magnet with a 



EMfi 



Fig. 02. Diagkam of a piece of muscle-fibue. 



north and a south pole. These small molecular mag- 

 nets being all arranged in the same order, somewhat 

 as is shown in figure 61, they act in combination in 

 the whole magnet ; but each separate j^art also acts in 

 the same way. 



The muscle may be similarly conceived. A stri- 

 ated muscle consists of fibres, all of which in the case 

 of a regular muscle-prism run parallel to each other, 

 and are of equal length. Each fibre must be regarded, 

 according to that which was said in Chapter I. § 2, as 



