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The influence of intravenous injections or infusions of insulin (0·2 i.u./kg), propranolol (150 mg), 3,5-dimethylpyrazole (3 mg/kg), 3,5-dimethylisoxazole (0·08 mg/kg), glucose (0·5 g/kg), nicotinic acid (120 mg/kg), arginine (0·5 g/kg) or butyrate (0·5 mmol/kg) on plasma glucose levels, and on serum concentrations of growth hormone and free fatty acids of lactating cows was investigated. In all of these experiments we noted an increase in the level of growth hormone. This increase was not a direct consequence of alterations in the glucose concentration, since the growth hormone peak occurred both during a decrease (insulin, 3,5-dimethylisoxazole, nicotinic acid and butyrate tests), and during an increase of the glucose level (glucose, arginine and propranolol tests), whereas the glucose concentration remained unchanged during the 3,5-dimethylpyrazole experiments. However, in each instance a precipitous fall of the free fatty acid level was noted.The glucose, growth hormone, and free fatty acid levels of lactating cows were not affected by either i.v. injection or infusion of saline.

A RELATIONSHIP between the level of ribonuclease activity and ribonucleic acid content has recently been found to exist in the human placenta1and in hyperplastic bone marrow of the mouse2; such a relationship has also been shown to exist in different normal organs of the mouse3, as well as different epitheliomas in mice or rats4. On the other hand, results obtained with solid4and ascites tumours5suggest that cancerous epithelium might have less ribonuclease activity than a normal one. We have undertaken a study of the properties of the human uterine cervix, from which homologous normal and cancerous tissues can easily be obtained.