On the percentage of water in the brain and in the spinal cord of the albino rat / by Henry H. Donaldson.

  • Henry Herbert Donaldson
Date:
1910
Catalogue details

Licence: In copyright

Credit: On the percentage of water in the brain and in the spinal cord of the albino rat / by 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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    of the spinal cord which for a given age is relatively somewhat greater in the male than in the female (Donaldson, ’09 pp. 163- 164). The effect of this lengthening would be to diminish the percentage of water. The influence of passive lengthening is dis- cussed more fully later on. Theoretic curves. When we take the more extensive series of mean values which is that for the males as given in table 1, and draw the theoretic curves based on them, we obtain the rela- tions shown in chart 3, the entries being arranged according to body weight. The data for this chart are given in table 3. For the formulas for these curves, I am indebted to Dr. Hatai. The formulas for the percentage of water in the brain of the male albino rat are as follows: Up to a body weight of 30 grams y = 99.5 — 12.6 log (x + 3.5) [1] and from a body weight of 30 grams on y = 82.62 — 2 log (x - 10) [2] In the case of the percentage of water in the spinal cord of the male albino rat we have for body weights up to 35 grams y = 94.9 — 12.8 log (x) [3] and from a body weight of 35 grams on y = 85.2 — 6.5 log (x) [4] In all these formulas y = the percentage of water and x = the weight of the body in grams. The formulas are of the same type as those used to express the growth changes described in several previous investigations (Donaldson ’08, ’09; Hatai ’09), and have their main value as convenient expressions of the several series of observations. Calculations (based on table 1, down to and including the entries for 275 grams body weight) show that in general for given body weight, the females which are under these conditions relatively older as compared with the males, have a percentage of water lower by 0.37 per cent in the brain and 0.60 per cent in the spinal cord. The theoretic values for the female can there- fore be obtained approximately by applying these corrections to the determinations here given for the males. Having thus presented the data on the percentage of water
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