300 CIRCULATION. 



other vascular parts, there is unquestionably congestion of the 

 vessels ; but there is no positive evidence of stagnation of 

 blood in the parts as a constant occurrence. The circula- 

 tion seems, indeed, to be more active than in health. With 

 regard to the microscopic phenomena just mentioned, the 

 contraction of the arterioles is simply the effect of a stimulus 

 upon their muscular coats ; and dilatation takes place prob- 

 ably in consequence of the excessive contraction, for it has 

 been shown that this condition of the muscular fibres is pretty 

 constantly followed by unusual relaxation. It has never yet 

 been determined how far the stasis of the blood is due to an 

 osmotic action of solutions employed in observations of this 

 kind. 



