136 VASCULAR SYSTEM. 



.#. The want of impulse, the solidity of the liver, the 

 absence of hepatic dilatation and contraction, all render 

 the circulation much more uniform than it is in the lungs 

 where the black blood system terminates. 



Q. Do the coats of the abdominal veins differ in strength 

 from those of the general circulation? 



*fl. They are of the same firmness. 



Q. What aids the circulation of blood through the ab- 

 dominal veins? 



#. The movements of the diaphragm and abdominal 

 muscles; the motion, dilatation and contraction of the 

 hollow viscera; the constant motion of the intestines. You 

 will observe that in the haemorrhoidal veins, that not 

 having these aids in their circulation, there are very fre- 

 quent varicose enlargements. 



Q. What induces the belief that the liver performs some 

 very important though unknown office in the system? 



A. The v great disproportion between the size of the 

 liver and its excretories and reservoirs, and that of the 

 kidneys, salivary glands, pancreas and their emunctories; 

 the greater flow of secreted fluids from the test mentioned 

 viscera than from the liver, although that is in size greater 

 than all of them collectively taken; the fact that the liver 

 is universally found in animals; the early foetal develope- 

 ment of the viscus, its being coeval with the heart and 

 brain; the great influence the passions have over it; the 

 conspicuous part it performs in the diseases of the ceco- 

 nomy; the influence of the liver on temperaments; its 

 frequent organic diseases; all these impose the belief sug- 

 gested in the question. 



Q. Does the liver effectuate any change on the vena 

 portal blood? 



