680 CARREL— FURTHER STUDIES ON [November 6, 



a very large increase of the interstitial connective tissue of the 

 media. The venous wall becomes as strong as the arterial wall. 

 The function has created the organ. Therefore, veins can act as 

 a substitute for arteries. This is of practical importance in human 

 surgery, for on the patient himself an abundant supply of vein can 

 always be found. 



The organs, kidneys, spleen, or thyroid gland, for instance, can 

 be transplanted from an animal to another animal and their circu- 

 lation immediately reestablished by suture of the blood vessels to 

 those of their host. Two methods are used — the simple trans- 

 plantation, and the transplantation in mass. The simple trans- 

 plantation consists of dissecting the organ, cutting its vessels, and 

 uniting these vessels directly to those of the host. In the trans- 

 plantation in mass, the organ is extirpated, together with the sur- 

 rounding tissues and organs, its nerves, vessels and the main vessels 

 of the region. After transplantation, the anastomoses are not made 

 on the vessels of the organ themselves, but on the main vessels of 

 the anatomical region. The transplantation in mass of the kidneys 

 has been performed on cats. It consists of extirpating from a first 

 animal both kidneys, their vessels and the corresponding segments 

 of the aorta and vena cava, their nerves and nervous ganglia, their 

 ureters and the corresponding part of the bladder; of placing these 

 anatomic specimens into the abdominal cavity of a second animal 

 whose kidneys have been previously resected and the aorta and 

 vena cava cut transversely ; and of suturing the vascular segments 

 between the ends of the aorta and vena cava, and of grafting the 

 flap of bladder onto the bladder of the host. In every case the 

 reestablishment of the renal functions was observed. These func- 

 tions were determined by the character of the urine and the general 

 condition of the animals. 



The secretion of urine often begins as soon as the arterial circu- 

 lation is reestablished. In some cases the amount of urine during 

 the first twenty-four hours was more than lOO c.c. However, a cat 

 urinated only 25 c.c. during the first twenty- four hours ; the second 

 day the amount of urine passed was only 16 c.c. ; this urine was 

 highly concentrated and contained much urea. Every cat urinated 

 abundantly every day, but the animals presented sooner or later 



