g54 LECTURE VI. 



ever, curious, that the hen*s spur grew to a 

 greater size on the cock's leg than it would 

 have done upon the parent animal, which 

 Mr. Hunter considered as a proof of the 

 greater vigour of constitution of the male 

 bird. 



Next to the organs concerned in the cir- 

 culation and aeration of the blood, Mr. 

 Hunter displays the various kinds of kid- 

 nies allotted to different animals as a speci- 

 men of glands in general, and as the agents 

 by which the impurities are carried off from 

 the circulating blood. Carbone and water, 

 with trivial quantities of saline and animal 

 substances, are discharged from that fluid 

 from the surfaces of the body, both from 

 the skin and lungs. The kidnies also carry 

 off redundant water from the blood, whicli 

 is a proper vehicle for salts casually re- 

 ceived or accidentally formed; but which 

 is likewise made to suspend various kinds 

 of solid animal matter. As many of the old 

 materials of the body, and some of the un- 

 assimilated matter of our food, are insoluble 

 in water, nature has given the kidnies 



