VOL. 4 (1950) ABNORMALITIES IN CELL DIVISION 299 



seen if the treated animals are maintained on a low protein diet (Elson and Haddow*^). 

 This finding indicates that the inhibition of growth is probably due to interference with 

 protein metabolism which can be overcome if the protein intake of the host is sufficiently 

 high. As 1:2:5: 6-dibenzanthracene causes abnormalities of chromosomes these ex- 

 periments suggest that chromosomes require an adequate supply of amino-acids for 

 their proper maintenance. 



The rates of diffusion and reaction are probably important characteristics of the 

 nuclear poisons which have been discussed. The compounds must, presumably, react in 

 or near the nucleus to produce their effects. For this they must diffuse through the cell 

 to the nucleus more rapidly than they react with the constituents of the tissue through 

 which they are passing, unless they have a specific affinity for the particular constituents 

 concerned with nuclear behaviour. The aliphatic nitrogen mustards react very rapidly in 

 the body, having a life of only a few minutes, but they do not react instantaneously 

 with any reagent and diffuse rapidly so that some unchanged molecules may reach 

 the nucleus. 



The evidence put forward supports the theory that chemical carcinogenic and 

 therapeutic agents for cancer combine with tissue constituents and that physical agents 

 cause some chemical change in chromosome constituents. -Goldacre, Loveless, and 

 Ross^^ suggest that it is the chromosomes themselves which are affected while the 

 author considers that the effects are due to inhibition of enzymes concerned in metabolic 

 processes involved in maintenance and functioning of the chromosomes. 



This investigation has been supported by grants to the Royal Cancer Hospital from 

 the British Empire Cancer Campaign, the Jane Coffin Childs Memorial Fund for Medical 

 Research, the Anna Fuller Fund, and the U.S. Public Health Service. 



SUMMARY 



1. The association of the effects of chromosome damage, induction of mutations and induction 

 of cancer with a number of agents is discussed. 



2. Examination of the reaction of a series of carcinogenic compounds with perbenzoic acid shows 

 that carcinogenic hydrocarbons react more rapidly than simpler non-carcinogenic hydrocarbons and 

 at about the same rate as nitrogenous aromatic carcinogens. 



3. The suggestion that the nitrogen mustards and possibly other carcinogens produce their 

 effects by inhibition of enzymes necessary for normal functioning of cell nuclei is considered. 



RESUME 



1. La relation entre les lesions des chromosomes, I'induction de mutations et I'induction du 

 cancer par un nombre d'agents est discutee. 



2. L'examen de la reaction d'une serie de composes cancerigenes avec I'acide perbenzoique 

 demontre que les hydrocarbures cancerigenes reagissent plus rapidement que les hydrocarbures non- 

 canc^rigenes et a la meme vitesse a peu pres que les substances cancerigenes azotees aromatiques. 



3. La suggestion que les moutardes azotees et peut-etre d'autres substances cancerigenes pro- 

 duisent leurs effets en inhibant les enzymes necessaires pour le fonctionnement normal du noyau 

 cellulaire est consideree. 



ZUSAMMENFASSUNG 



1. Das Verhaltnis zwischen Chromosomenverletzung, Hervorrufen von Mutationen und Krebs- 

 bildung durch verschiedene Agentien wird diskutiert. 



2. Die Untersuchung der Reaktionen einer Reihe von cancerogenen Verbindungen mit Per- 



References p. 300. 



