218 A. V. LEBEDINSKY, V. M. MASTRYUKOYA AND A. D. STRZHIZHOVSKY 



orange stain); Plate II shows the same object after tlie stimulation of 

 the elements of the first trigeminus branch, the disintegration of nucleic 

 acid being seen distinctly. Plate III shows a more strongly pronounced 

 picture of the DNA disintegration which appears after the destruction of 

 Gasserian ganglia. 



No doubt, extracellular factors do exist and play a definite role in 

 DNA changes arising during exposure of l^iological objects. They 

 should play a definite role in the i*eactions to exposure. This ensvies 

 from the experiments of Kuzin and Budilova (1953, 195-t) who showed 

 that the changes of nucleic acids in the spleen vary in relation to 

 whether exposure was local or whether the animal's head was sub- 

 jected to irradiation. 



Similar experiments do not yet show that disturl)ances of DNA 

 synthesis arising in the cell as a secondary matter (under the effect of 

 extracellular factors) are related to mitotic activity. However, special 

 experiments have been carried out which showed that it was undoubt- 

 edly so, for instance, experiments with adrenaline inhibiting mitosis 

 (Alov, 1956; Strelin, 1954). According to our experiments deoxycorti- 

 costerone acetate (DOC A) has a definite effect as well. 



Figure 4 shows changes in the relative mitotic activity of the corneal 



Fig. 4. — The offoct of DOCA on tlie mitotic aeti\-ity of the corneal epith(>liuiii of the 

 mouse. 



100 per cent is taken as the norm. 



