98 Animal Morphology. 



so local electric changes will become early notified to the 

 heart before the mass of blood suffers any important change. 

 Moreover, the minute arteries will be depressed or excited 

 in their muscular walls by the local condition of electricity, 

 and the part itself will be the first partaker of any change 

 of circulation of a retarded or accelerated nature. 



This would well explain Haller's observations on the 

 increased local circulation in inflammation ; for if it began to 

 increase locally the current of blood in the arteries of the 

 affected part or limb by stimulation and dilatation of them, 

 then, as a sequence, the venous blood would become pro- 

 portionally increased in amount, and end in local plethora. 



But if the heart and vessels were all one membrane, the 

 more active function of the heart must be more or less 

 in abeyance to, or in harmony with, the slow contractile 

 powers in the larger vessels ; and the contraction and dila- 

 tation of the arterial system must keep pace with the quick 

 or slow action of the heart, which would subject the circula- 

 tion to too sudden and extensive changes, and would prove 

 a source of great danger. 



We now leave the membranes more especially concerned 

 in vegetative life and turn to the tripartite membranes of 

 animal life. 



The mammary tripartite membrane has already been 

 examined and viewed as essentially transitionary ; whilst 

 the veno-arterial membrane was considered an essentially 

 diffused vegetative membrane, and fulfilling the ordinary 

 chemico-vital function -of a mucous membrane in the 

 ramifying capillaries pertaining to muscle, bone, and nerve 

 belonging to animal life, and other membranes in fact, to all 

 membranes external to itself; and when, from peculiar circum- 

 stances, the ordinary functions of chemico-vital forces are 

 inadequate to minister complete efficiency whilst supplying 

 the wants and removing the debris of the essential organs 



