108 VASCULAR SYSTEM. 



Jl. The veins, the right side of the heart, and the pul- 

 monary artery. 



Q. How are the valves of the veins and arteries formed? 



,#. They are formed from the continued lining mem- 

 brane of these vessels. 



Q. What is the conspicuous anatomical view to be taken 

 of those two circulations? 



#. Their entire separation, their distinctness, and the 

 respective origin and terminations of the two in the pul- 

 monary and general capillary systems. 



<J. What do you mean by their distinct and separate 

 character? 



*#. It is, that separate organization supports them. Even 

 if the right and left sides of the heart were not united, the 

 two functions would readily proceed. 



Q. At what point in the channels of the respective cir- 

 culations do you find the greatest collection of blood? 



A. In the heart. 



Q. What general arrangement of the channels is worthy 

 of recollection ? 



Jl. That the vessels which convey red blood from the 

 commencement of its circulation to the heart increase in 

 size and diminish in number; that the vessels which con- 

 vey red blood from the heart to its termination increase 

 in number and diminish in size. The same fact obtains 

 in the arrangement of the vessels conveying black blood, 

 viewing its vascular system as commencing in the general 

 capillaries and terminating in the lungs. . 



Q. What renders the heart necessary in these two red 

 and black blood systems? 



*#. Without it the parietes of the vessels could not con- 

 vey the blood from one capillary system to another. 



