PER1PHERIC ORGANS OF THE CIRCULATION. 141 



into five parts representing the length of a cardiac revolu- 

 tion, register, as follows, the time of each of these movements 

 and of the corresponding sounds : 



II. PERIPHERIC ORGANS OF THE CIRCULATION. 



A. Mechanical arrangement of these organs. 



We have seen that there is an artery which begins in the 

 ventricle, and becomes, as it continues, more and more rami- 

 fied (A). In a mechanical or hydrostatic point of view we 

 may leave out of consideration 

 the ramified form of the arterial 

 tree (Fig. 40) ; that is, in plac- 

 ing all the arterial trunks (B) 

 in juxtaposition, we need not 

 take into account all the parti- 

 tions which result from placing ' 

 the vessels side by side (C). Fig. 40. 



. . * . \ ' Diagram of a vascular cone.* 



Now, as it is proved that when 



a vascular trunk is divided, the sum of the containing space 

 in the two branches is always greater than that of the prim- 

 itive trunk ; so that the capacity of the system increases the 

 farther it is removed from the aortic trunk, we obtain, in the 

 diagram made as above described, a conic figure of the arte- 

 rial system (Fig. 40 C). This cone will spread out like a 

 tent, and the widening will be considerable at the arterial 

 extremities (base of the cone), because the bed in which the 

 blood circulates is greatly enlarged as it approaches the 

 capillaries (Fig. 41). The same principles being applied to 

 the venous system, the latter may be theoretically represented 

 by a cone placed with its base in opposition to the cone of 

 the aorta, the common base representing the capillary system, 

 and thus forming a short cylinder placed between two cones 



* Construction of a vascular cone, an arterial cone, for instance. A, Artery, 

 bifurcated repeatedly. In B the bifurcated branches are supposed to be brought 

 close together, giving rise to a partitioned cavity. In C, by removing these par- 

 titions, we tiud that the whole of the primitive trunk and* its divided branches 

 form a cone. 



