An interpretation of some differences in the percentage of water found in the central nervous system of the albino rat and due to conditions other than age / Henry H. Donaldson.

  • Donaldson, Henry Herbert, 1857-1938.
Date:
1911
Catalogue details

Licence: In copyright

Credit: An interpretation of some differences in the percentage of water found in the central nervous system of the albino rat and due to conditions other than age / Henry H. Donaldson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    While the excess of the percentage of water in the brain might be connected with the slightly greater brain weight in the exer- cised group, there is no corresponding deficiency in the weight of the spinal cord to explain the deficiency of water found in it. As the matter stands then, the data do not permit of any conclu- sion except that the percentage of water in the central nervous system is not definitely modified in exercised rats. (2) Watson (’05) found that rats bearing young, as contrasted with unmated rats of the same litters, had a somewhat greater body weight, a brain weight which was the same, but a distinctly heavier spinal cord, while the percentage of water on the average was as follows: BRAIN SPINAL COED Mated 77.47 68.51 Unmated... 77.37 68.29 Difference, mated +0.10 +0.22 In commenting on these relations it can be said at the outset that there is no question that it is characteristic of mated animals to have a slightly greater percentage of water in the central nervous system, for it occurs in nine out of the ten comparisons which can be made with these data—but how it comes about is not so clear. There is no conclusive evidence that the mated rats have heavier brains, yet they do have 0.1 per cent more water in the brain. On the other hand, with the distinctly heavier cords of these rats goes 0.22 per cent, more water. Also the mated rats have about 9 per cent more body weight. In this case therefore the greater amount of water in the central nervous system can be most simply related to the more vigorous growth of the body as a whole. (3) Hatai (’07) found that the effect of severe underfeeding for twenty-one days, followed by a return to the normal diet, yielded, at two hundred days, animals of nearly the same weight as the controls; indeed the rats which had been subjected to underfeeding were on the average a little heavier than the controls, while the weight of the central nervous system was not modified by this treatment.