ORGAN AND BODY SYSTEMS 499 



off as the material is excreted into the intestine (187). Usually this 

 damage is of the chronic type because of the low dosage involved. Other 

 parts of the body, of course, are subjected to irradiation from these sub- 

 stances, but changes in other organs will be discussed in their proper 

 place. 



Colon. — While no great amount of work has been done directly on the 

 colon, the experiments described by many workers (Regaud, 291; Mar- 

 tin et al., 207; Warren et al., 371) show that it is more resistant than 

 the small intestine, probably about equal in sensitivity to the 

 stomach. The predominance of mucus-secreting cells in damaged areas 

 would suggest that this type of cell is more resistant than the other 

 types. This finding compares favorably with observations on similar 

 cells of the stomach and small intestines. The mucosa of the rectum has 

 essentially the same sensitivity characteristics as the mucosa of the 

 mouth. 



Bladder. — The bladder, being lined with pavement epithelium, 

 would be expected to have about the same relative sensitivity as the 

 skin. This similarity seems to be borne out by clinical observations 

 following the application of radium. The acute experiments on dogs 

 seem to support this belief, though no work has been done directly 

 upon the bladder. In experiments where the animal has been given 

 generalized irradiation, the bladder shows no acute changes, though it 

 is possible that neither the dosage nor the time intervals used were within 

 the proper limits. The same is probably true of the rest of the genito- 

 urinary tract not including the kidney, though there is little or no experi- 

 mental work to suggest this. Martin and Rogers (209) found that 

 53 mg. hr. of radium applied in steel needles alongside the ureter in 

 dogs produced a partial stricture, while 75 mg. hr. produced complete 

 stricture. 



Pancreas. — In the acute experiments dealing with the effects upon 

 the intestinal tract all the workers agree that the pancreas is not damaged 

 by doses and time intervals within the scope of these experiments. There 

 is no direct experimental evidence that the pancreas can be damaged by 

 the irradiation in situ, without producing severe and eventually fatal 

 damage to the small intestine, except for a diffuse fibrosis noted by 

 Doub {et al., 83, 84) in 2 dogs out of a very large number exposed in the 

 kidney region. The sugar metabolism was not disturbed. Orndorf, 

 Farrel, and Ivy (256, 257) studied the effects of Ko> }i> and 1 human 

 erythema dose on the function of a piece of pancreas transplanted under 

 the mammary gland of the dog. They used 150 kv. (effective wave- 



o 



length of 0.181 A). One-tenth erythema dose increased the concentra- 

 tion of lipase and trypsin but did not change the quantity. One-half 

 human erythema dose increased the quantity and total output of fer- 

 ments. One erythema dose decreased the quantity of ferment and total 



