AND ANIMAL LIFE. 405 



easily adapt themselves to a continued distend- 

 ing power, but, as this force is frequently exert- 

 ed, a rupture of vessels necessarily takes place. 



CCCCLXXXIV. Hemoptysis, at a later pe- 

 riod of life, is supposed, by the same author, to 

 arise from the balance being destroyed " between 

 the systems of the aorta and pulmonary artery, 

 or between the vessels of the lungs and those of 

 all the rest of the body." 



CCCCLXXXV. As hemorrhagies of a passive 

 character are often remarked at a time of life 

 much later than the two preceding, he has brought 

 forward a truly ingenious hypothesis to explain 

 the origin of these diseases ; but it is not, perhaps, 

 less chimerical than the former reasons he ad- 

 duces. He observes, that the veins in early life 

 have a greater proportional density than the arte- 

 ries, and that on this account they are enabled to 

 propel with greater energy their contents into the 

 latter, and in this way they subsequently become 

 distended or engorged, giving rise to epistaxis 

 and hemoptysis ; but, towards the decline of 

 life, the arteries have their cellular texture in- 

 creased by distention, and from this cause they ac- 

 quire a greater proportional density than the 

 veins, so that these are liable to receive more 

 blood than they can possibly circulate. 



CCCCLXXXVI. In place of explaining the 

 preceding phenomena on the supposition of this 

 or that organ being the soonest completed, or 



