400 BIOLOGY: GENERAL AND MEDICAL 



plication and rearrangement form the new epithelial 

 covering. 



Certain of the mucous membranes are also able to 

 survive transplantation, and good results have followed 

 plastic operations in which fragments of tissue from 

 the mouth have been used to assist in the restoration 

 of destroyed conjunctiva. 



3. The amputated part is transplanted to another animal 

 or plant of the same kind. 



Under such circumstances the new environment to 

 which the graft is transplanted differs from that of the 

 autoplastic grafts in so far as the physiological condi- 

 tions of two individuals may differ. As has been shown 

 in the chapter upon Blood Relationships, the chemical 

 and physiological conditions among individuals of the 

 same species are usually, but not necessarily, identical. 

 When they happen to differ, the grafts may fail exactly 

 as when the grafts are heteroplastic. 



Were it not for physiologico-chemical variation, this 

 form of transplantation might be looked upon as the 

 future hope of surgery, for Carrel has shown its extraor- 

 dinary possibilities. Thus he has removed the kidneys 

 of a cat and replaced them by the kidneys of another 

 cat. The animal recovered from the operation and 

 lived on in apparent health for some time. He has 

 also transplanted a limb from one dog to another dog, and 

 removed most of the tissues from one side of the face of 

 one dog to the corresponding situation upon another dog. 



These results justify the hope that the time may not 

 be far distant when normal kidneys from a normal person 

 killed by accident may be implanted into the body of 

 another whose kidneys are diseased, and that a part of a 

 limb amputated for traumatic injury or taken from a 

 person suddenly killed by accident may be used to 

 supply a limb needed by some other person whose mem- 

 ber is lost through disease. Indeed, a knee-joint has 

 already been thus transplanted from one man to another 

 with success. 



