The action of some endosuccinic acids derived from polycyclic hydrocarbons on the red blood corpuscles of the mouse.

STRONG [1936] and Strong & Francis [1937] have described a fall in the haemoglobin content of the blood of female mice of strains which are liable to the development of spontaneous mammary carcinoma. The experiments of Parsons and her collaborators have shown that general irradiation of mice or rats with sub-lethal doses of X-rays increases and accelerates tumour production on subsequent treatment of the animals with a carcinogenic compound [Mayneord & Parsons, 1937; Clarkson et al. 1938; Parsons, 1938]. This change produced by the X-rays is one affecting the haemopoietic system; the red blood cells are diminished (in rats) and iron is deposited in the lymph glands. Parsons and her fellow-workers have also shown that the same signs of blood destruction are present in mice undergoing treatment with a carcinogenic substance. Application of the prussian blue reaction to sections of the lymph glands of these animals before the appearance of tumours revealed the presence ofiron. In a forthcoming publication the present author will adduce quantitative estimations of iron in support of these microscopical observations. In view of these results it was considered of interest to carry out some simple in vitro experiments on the action of the compound used by Parsons and co-workers. The experiments were ultimately extended to embrace a series of similar compounds derived from carcinogenic and closely related noncarcinogenic hydrocarbons. The choice of the hydrocarbons to be used was necessarily restricted to those which yield adducts with maleic anhydride. For example, phenanthrene and 3:4-benzphenanthrene were excluded by this condition and, so far, all efforts to obtain an adduct from 3:4-benzpyrene have been unsuccessful. MATERIALS