Abstract
Earlier experiments 1 on the effects of solutions of various salts on brain cells have led indirectly to this study of imbibition of water in salt solutions by whole brains of white rats.
The rat's brain was chosen in order to find the reaction of the whole organ, so that the relation of surface to mass should be relatively constant. As might have been anticipated, Parry 2 found this relation to be a factor in variations in the degree of swelling of muscle tissue.
If the swelling is not allowed to go on until a constant is reached, comparisons are open to error, and since brain tissue is so rapidly hydrated when left in water or in salt solutions of any degree of hypotonicity, it seemed that small total brains might yield more satisfactory results than larger brains or blocks of tissue. In the case of the latter, the difference in the swelling capacities of gray and white matter is a point of special significance in making comparisons.
The brains were removed from young animals up to 10 days of age after decapitation; in older ones, after ether. The removal was done rapidly, they were weighed immediately and placed at once in the various solutions. The results are based on more than 300 weighings.
The fluid series was made up of distilled water alone, Ringer-Tyrode solution, sodium, potassium, magnesium and calcium chlorides in distilled water at a concentration iso-osmotic with Ringer's solution.
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