154 THE ORGANS 



them only by reference to their development from more simple 

 structures. 



From the foregoing it follows that in studying an organ there are 

 to be considered primarily: 



(i) The specific tissue of the organ. (Parenchyma.) 



(2) The connective tissue framework. (Interstitial tissue.) 



(3) The blood supply. 



(4) The nerve supply, 



(5) Function. 



(6) Development. 



