ON THE INFLUENCE OF ASPHYXIA UPON THE ACTION OF CONVULSANT DYES AND UPON THEIR ENTRANCE INTO THE SUBSTANCE OF THE CENTRAL NERVOUS SYSTEM. II

¹ Psycho-Biological Laboratory, Henry Phipps Psychiatric Clinic, Johns Hopkins Hospital, Baltimore, Maryland

1. Asphyxia produced by placing frogs under water, under white oil, or in a nitrogen atmosphere increases the convulsive action of acid fuchsin. Doses (ordinarily ineffective) of 0.3 to 1.0 mgm. per 1 gram body weight cause a convulsive reaction from eight to fifty-five minutes after the asphyxia has started, less time elapsing on the average in those instances where the oxygen has been completely eliminated (oil, nitrogen, and boiled water). The asphyxia also causes an increased absorption of the convulsant dye (acid fuchsin) by the central nervous system. Two conditions can be distinguished as results of the chemical changes which take place in asphyxia: first, an increased readiness of the nervous system to react to convulsant drugs, and second, an increased absorption of the dye. The increased absorption is considered to be due to an increased permeability of the cerebral vessels and, perhaps, of other structures in the central nervous system.

Potassium cyanide, which, itself, causes slight spastic movements, also increases the action of acid fuchsin, an effect thought to result from the asphyxia due to the administration of the cyanide.

2. By microscopic observation and microphotography a slight local dilatation of the cerebral capillaries in the living frog could be seen to follow mechanical stimulation of the surface of the brain.