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DISCUSSION 



Rose: Most of our work over the past ten years with alkylating agents 

 in general, such as those mentioned by Dr. Alexander, has been in the 

 cancer field, but in this last year or two we have investigated their effects 

 in the field of microbiology. The substance I want to mention now is one 

 of the very simplest derivatives of ethyleneimine, namely acetyl ethyl- 

 eneimine. This substance is freely soluble in water, gives neutral solu- 

 tions, neither anionic nor cationic, and its chemistry is rudimentary. 

 Yet this substance is a frank carcinogen. Doses of no more than 1 mg./kg. 

 body weight, given subcutaneously into the flank of a rat, produce local 

 sarcoma in very high yield : out of a dozen rats you can usually get at 

 least ten of them bearing tumours, after a period of 200 days onwards. 

 A few tumours are often formed at distal points, for example in the 

 sebaceous glands of the ear, and so on. However, we feel convinced that 

 this substance is a direct carcinogen. Fairly recently Dr. Pryce has been 

 examining the action of this substance on chromobacteriiim prodigiosum 

 {Serratia marcescens), the organism which produces the tripyrryl red 

 pigment, prodigiosin. Pryce incubates this organism in the usual way 

 in broth, and harvests the organisms towards the end of the logarithmic 



