52 ELECTRO-PHYSIOLOGY 



not only supported by the changes in volume (supra) of the two 

 chief systems of segments in each fibril, but is also confirmed by 

 the diminution of double refractibility already mentioned in con- 

 traction, as well as by the fact that under these conditions the 

 isotropous (arimetabolous) bands appear darker and less trans- 

 parent. The anisotropous, on the contrary (with the exception 

 of the middle disc), is clearer and more transparent in ordinary 

 light. In proportion as the segments (Q) (dark bands) imbibe 

 water from the isotropous system, they must become not only 

 more voluminous, but also less refractile, and clearer, as well as 

 less doubly-refracting. The isotropous bands, on the other hand, 

 would become smaller and more refractile, and darker in appear- 

 ance, as is actually the case. Finally, the alterations in colour 

 of the contracted section of the fibre agree well with the theory 

 that the anisotropous segments swell at the expense of the 

 isotropous. The colourability of turgescent bodies, as well as 

 their chemical constitution, is known to depend in great measure 

 upon the degree of turgor at the moment. The rule for each 

 single, turgescent, colourable mass is that it stains the more 

 intensely in proportion as it contains less water of imbibition. 

 As a matter of fact, increased colourability of the arimetabolous 

 (isotropous) bands can be observed during contraction, while the 

 metabolous (anisotropous) segments stain much less deeply with 

 heematoxylin than during the resting state. 



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