ORGAN AND BODY SYSTEMS 491 



longer end of the electromagnetic spectrum but has little effect probably 

 when the shorter (beyond 1 A) wave-lengths are used. The dosage is 

 the product of time and intensity. The massive tolerance dose and the 

 total fractional dosage of roentgen rays give almost equally severe reac- 

 tions from which the skin may recover though the margin of safety is 

 probably greater with the latter. Effective differences between long and 

 short roentgen rays of equal amounts (over equal areas) are so small as 

 to be of little importance in practice in so far as the skin is concerned. 

 The normal variation in the animal and human subject is probably as 

 great as if not greater than the difference in effect between the long and 

 short roentgen rays. 



THE EFFECT OF GENERAL BODY IRRADIATION 



If the whole animal organism (dog, rabbit, and most other experi- 

 mental animals) is irradiated (377) by rather high massive dose of roent- 

 gen radiation, i.e., approximately 2500 r, an acute rapidly developing 

 intoxication ensues, usually accompanied by bloody diarrhea and exitus 

 on the fourth or fifth day. There is evidence of rather widespread 

 damage to certain internal body structures without evidence of damage 

 to others. This is due partly to the specific sensitivity or resistance of 

 certain tissues to this dosage level and partly to the variation in the 

 appearance time of evidence of damage (i.e., latent period). It is 

 believed by some (377) that when the whole body or the abdomen is 

 irradiated, the major cause for the fatal intoxication is the rapid destruc- 

 tion and disintegration of the intestinal mucosa within the 4- to 5-day 

 period. A somewhat more complex though sharply limited syndrome is 

 likewise produced by irradiation of the bony skeleton with the abdomen 

 protected (334). In this type of experiment the destruction of bone- 

 marrow cells, while just as extensive as is the case in the intestinal epi- 

 thelium, causes only a sUght or moderate intoxication. Exitus in this 

 case is accompanied or precipitated by a progressive thrombocytopenia 

 and sudden widespread capillary hemorrhage (8 to 10 days). Other 

 acute syndromes may be produced by damages of the liver, etc., but these 

 have not been thoroughly studied. 



Profound chronic damage of serious and fatal type may likewise be 

 produced by total irradiation because of the production of widespread 

 sloughing of the skin and muscle or diffuse degeneration of intestinal epi- 

 thelium, or by means of intensive localized irradiation of certain vital 

 organs such as the heart or kidneys (84). In such circumstances exitus 

 occurs usually by secondary infection of the tissues through the skin 

 ulcers or by functional disability and failure of the organ, i.e., slow 

 starvation from inadequate digestion and absorption of food, etc. In all 

 areas irradiated in such a manner many other structures are damaged, 

 such as lymphoid tissues, gonad cells, blood vessels, and connective 



