138 BARBARA E. HOLMES 



cerned in this the energy conld probably be utihzed in some part of the 

 DNA or be available for release in the protein closely associated with it. 

 The secondary effects of snch an initial process conld be different 

 according to the exact condition of the DNA. The irregnlar chromosome 

 structures sometime found in tumours, virus-infected nuclei, chromo- 

 somes with puff formation, DNA during the process of reduplication, 

 and so on, might suffer changes rather different from the usual. Pro- 

 fessor Mitchell himself is trying to determine whether the findings can 

 l)e related to the radio-curability of the tumour. At all events, there is 

 here a chance of seeing an absolutely initial effect and of investigating 

 its real meaning and relating it to the results which follow later. 



ACKNOWLEDGEMENTS 



1 am most grateful to the Wellcome Foundation for providing my travelling 

 expenses to this meeting. 



REFERENCES 



Andersox, N. G.. and Fisher, W. D. (1960). In "The Cell Nucleus", p. I'J.J. (J. S. 

 Mitchell, ed.) Butterwoi-ths, London. 



BoLLUM, F., and Potter, V. R. (1960). Caticer lies. 20, 138. 



Crathorne, a. R., and Shooter, K. V. (1960). Nature, Lond. 187, 614. 



FoRSSBERG, A. (1960). Congress of Pliotobiology, Copenhagen. In press. 



Gaulden. M. E.. and Perry, R. P. (lO.lS). Proc. not. Acad. Sci., Wash. 44, r)."i3. 



Gordon, S. (19.")6). In "Progress in Radiobiology". (Mitchell, Holmes and Smith, ed.) 

 Oliver and Boyd, Edinburgh. 



Holmes, Barbara E., and Mee, L. (1955). In "Proceedings of the Radiobiology Sym- 

 posium, Liege, 1954". (Z. M. Bacq, ed.). Butterworths. London. 



LooNEY, W.. Campbell, R. C, and Holmes. Barbara E. (1960). Proc. nat. Acad. Sci., 

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Mitchell, J. S. (1959). Eep. Brit. Emp. Cancer Campgn. 



Ord, M. G., and Stocken, L. A. (1960). In "The Cell Nucleus", p. 157. (J. S. Mitchell, 

 ed.) Butterworths, London. 



OsAWA, S., Allfrey, V. G., and Mirsky, A. E. (1951). ./. gen. Physiol. 40, 491. 



Pelc, S.. and Howard, A. (1953). Acta Radiol. Sup]>l. 1 1(>. Richards. 



Seed, J. (1960). In "The Cell Nucleus", p. 49. (J. S. Mitcliell, ed.), Butterworths, London. 



Schneider, J. (1960). J. biol. Chem. 235, 1437. 



Ungar, F., Rosenfeld, G.. Dorfman. R. I., and Pincus, G. (1955). Endocrinologi/, 56, 

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DISCUSSION 



TliMERMAN: I am very interested in the information on Prof. Mitchell's discovery 

 of nltraviolet emission during warming of frozen tissues. I would like to know 

 whether the temperature dependence of the intensity of this luminescence was 

 studied and what is Prof. Mitchell's or your opinion on the physical mechanisms 

 of the origin of this i-)henomenon. Are you inclined to consider this luminescence 

 as a chemiduminescence attendant upon a free radical recombination j)rocess, 

 or some oxidation reaction, or as a phenomenon of thermoluminescence resemb- 

 ling the known therniohiminescence of chloroplasts discovered by Arnold and 

 Sherwood? 



