GENERAL DISCUSSION 



349 



In experiments on local irradiation of the bones of a rabbit by a dose 

 of 2 kr the variation in the autolysis of the nucleic acids and also of the 

 content of free nucleotides took ])lace only in the irradiated extremities. 



The autolytic fission of the nucleic acids in the irradiated bone- 

 marrow may be seen from Fig. 3 to be reduced two or three times in 

 7 hr. The inhibition of autolysis of the nucleic acids within a long 

 period of time is irreversible, whereas the content of the free nucleo- 

 tides during this time approaches the normal. 



I 2 3 4 5 6 7 8 



Period after irradiation 



Fig. 3. — The variation of the rate of autolysis of nucleic acids and the content of the 

 acid-soluble purine and pyriuiidine compounds in the bone-marrow of a rabbit after 

 local X-irradiation with a dose of 2,000 r. 



1. The content of acid-soluble purine and pyrimidine compounds. 



2. The rate of autolysis of nucleic acids in homogenates of irradiated bone-marrow. 



It is evident that, within a very short time after X-irradiation the 

 nucleic acids of the tissues are strongly bi^oken down by nucleases. 

 The result of this is that a smaller amount of nucleic acid will remain 

 in the irradiated tissue. These nucleic acids, as Oparin has shown, will 

 inhibit proteolytic enzymes. It follows that the cause of the increased 

 autolysis of the proteins after irradiation is the reduction in the nucleic 

 acids in the tissue 



ASTAUROv: Experiments with irradiation of the nuclear and non- 

 nuclear parts of a cell with accurately-localized application by means 

 of micro-beams have shown that irradiation harms both the nucleus 

 and the cytoplasm. 



Although nuclear damage becomes dangerous for doses of between 



M* 



