ORGAN AND BODY SYSTEMS 515 



tions, no matter what the dose used and what the bone irradiated. 

 These changes were not in proportion to the changes in the circulating 

 blood. 



This procedure, of irradiating only a part of the marrow and studying 

 the stimulus or compensatory changes brought about in unirradiated 

 areas, should yield some valuable information regarding the response of 

 the bone marrow to the sudden needs of blood regeneration. Such work 

 should be done on dogs which have a stable hematopoietic system. 

 Further work with total destruction of the bone marrow should yield 

 very interesting information concerning the life cycle of the components 

 of the bone marrow or the myeloid series, but of course the experiments 

 will be complicated by the tendency of the animal to bleed, owing to the 

 thrombocytopenia. It is impossible at present to tell whether the 

 irradiated normoblasts in the marrow have matured into adult red blood 

 corpuscles or have been destroyed with a few surviving in statu quo. 

 Their precursors are evidently destroyed readily by the dosage used. 

 Total destruction of marrow activity with essentially similar results 

 may likewise be brought about by injection of sufficient amounts of 

 radioactive materials (30, 49, 186, 188, 326, 350, 360, 383). 



The coagulating power of the blood is not affected except in therapeutic 

 cases irradiated for castration or hyperthyroidism, where it fluctuated 

 in amount (200). Pagniez, Ravina, and Solomon (261) were unable to 

 show any changes in the coagulation time of the blood in vitro, but the 

 coagulation time was rapidly accelerated in most of their human cases of 

 blood dyscrasia with irradiation of between 100 to 500 r. There were a 

 few reports in which no reaction appeared (23, 308, 334). 



Pohle (274) studied the reticulo-endothelial system of rabbits exposed 

 to doses varying from 150 to 300 r over the spleen or over the whole 

 body. He points out that there is considerable variation in the effects 

 produced and believes that there is some increase of the speed of elimina- 

 tion of Congo red or trjrpan blue following these small doses (300 r). 

 Doubling the dose causes the changes to approach more nearly normal 

 values. The significance of these experiments is not clear, yet the idea 

 behind them is of merit. The use of graded dosage and a better method 

 of demonstrating functioning endothelial phagocytes might be of value 

 (cf. 399, 400). 



Thorsness (352) irradiated (34 to 3^ erythema doses) the foreign-body 

 reaction (aleuronate abscesses) in rabbits and found that the abscesses 

 were reduced in size and the absorption of the particulate materials 

 increased. Apparently there is an early degeneration of fibrin before the 

 tissues have established this function. There is destruction of lympho- 

 cytes and macrophages, and hyalinization and calcification in the areas, 

 the true destructive changes of these cells being evident one day after 

 irradiation exposure (see also 217). 



