OP THE MUSCULAR SYSTEM IN GENERAL. 423 



perceived on examining the heart of young animals while in 

 action; the apparent change of colour is only owing to its 

 transparency. 



673. Many physiologists have ascribed the. muscular ac- 

 tion to the accumulation of blood in the muscles, either in the 

 interior itself, or the invervals of the fibres; others to causes 

 analogous, all of which suppose an- augmented activity of the 

 circulation during the muscular action. Haller has already 

 offere^ many objections to these hypotheses. There is no 

 direct proof of the afflux of blood in the muscles during their 

 action. The experiments of Barzelotti. moreover prove that 

 the contraction 'of the muscles of the frog ? excited by galvan- 

 ism, can take place after death: 1st, when the blood no longer 

 circulates in the vessels; 3d, when the blood is even congealed, 

 and 3d, when, in fine, the vessels are deprived of blood altoge- 

 ther. The question, it is true, arises as to the cadaverous con- 

 tractions exerted by galvanism; but other' facts prove again, 

 that the presence of blood in the vessels of the muscles is not 

 necessary to their contraction. Nevertheless, it is known that, 

 when there is fluid blood in a muscle, contraction, even after 

 death, puts the blood in motion, as if by a kind of exposition. 



674. The fibres which were straight during the state of 

 relaxation, bend during contraction, forming very regular 

 sinuosities. These sinuosities or folds, before perceived' by 

 numerous observers, have been carefully examined by Messrs. 

 Prevost and Dumas, who have recognised these zigzags a* 

 being always produced in the same manner, and that the apex 

 of the angles, which are the points of the fibre that approach 

 each other outside of the line of con-traction, are also those 

 where the last traj^verse ramifications of the nerves ter- 

 minate. 



675. During the contraction of the muscles there exists a 

 continual fibrillar agitation* in their thickness; some of the 

 fibres contract, while others are relaxed. It is to this cause 

 that we must ascribe the noise that is heard when the finger 



* Roger, de perpetud fibr. must, palpitatione; Gott, 1760.-r-Wollaston, 

 .Croonian Lecture, in Philos. Trans.; Ann. 1810. 

 55 



