SECTIONAL TRANSACTIONS.— B. 



407 



organs of the male or on the atrophic or undeveloped organs of the female — 

 it has no androgenic or cestrogenic power. 



The androsterone-testosterone group comprise three compounds which 

 have been isolated from natural sources and a large number which have 

 been prepared artificially. Most of these are able to stimulate the atrophic 

 accessory organs and secondary sexual characters of castrated animals, i.e. 

 they are androgenic. Many of them are gynaecogenic in that they will 

 stimulate development of the reproductive tract in immature or ovariecto- 

 mised females, while at least one, trans-androstenediol, is cestrogenic in 

 the sense that it will cause cornification of the vagina in mice. Testosterone 

 and several other androgens when methylated in position 17, have the 

 progesterone-like power to cause progestational changes in the uterus. 



Several of the androgens are able to depress the activity of the pituitary 

 and cause atrophy of the gonads with consequent inhibition of the sexual 

 cycle of the female. A similar indirect effect is also responsible for the 

 depression of adrenal development seen in the male mouse, or in the female 

 or castrated male receiving androgen. 



Both progesterone and the androgens are able to protect the organism 

 from certain eflfects of the cestrogens, an action which may be partly respon- 

 sible for the eflfect of androgens on the intact female. 



Prof. J. W. Cook, F.R.S. — Polycyclic hydrocarbons with cancer- 

 producing action (11. 15). 



There is now a considerable group of polycyclic aromatic hydrocarbons 

 which have the power of causing cancer. The disease so produced is 

 indistinguishable in its characteristics from that which occurs in man. The 

 chief classes of cancer-producing hydrocarbons are {a) those derived from 

 I : 2-benzanthracene (I) and {b) 3 : 4-benzphenanthrene (II) and its 

 derivatives. 



(I) 



The former class has been extensively investigated and it is now possible 

 to state some of the factors of molecular structure which are associated with 

 cancer-producing activity. The twelve monomethyl derivatives of 1:2- 

 benzanthracene have been synthesised and tested, and the only ones which 

 have shown definite carcinogenic action are those with the substituent at 

 positions 10, 5, 9, 6 (this represents a decreasing order of efficiency). 

 Further, if simple alkyl substituents are present in two favourable positions 

 of substitution they reinforce one another so that more potent compounds 

 result. Such compounds are the 5 : 6-dimethyl and other 5 : 6-substituted 

 benzanthracenes (Cook), 5 : 9-dimethyl-i : 2-benzanthracene (Newman) 

 and 5 : lo-dimethyl-i : 2-benzanthracene (Fieser). 



The most powerful carcinogenic agent so far known is 9 : lo-dimethyl- 



