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SHIGEYUKI KOMINE 



values in which the influence of the difference in brain weight is 

 entirely eliminated. The exact method of correction is given 

 by Donaldson ('16) and for it the reader is referred to that paper. 

 The percentage of water in each instance, as thus calculated, is 

 also given in table 2. We notice that the differences obtained 

 when the calculated values are used are practically identical 

 with those obtained by the use of the observed values, but since 

 the observed brain weights were small for their age, the absolute 

 observed values for the percentage of water in both control and 

 test rats run above those which are calculated. We have, how- 

 ever, chosen the calculated values of the percentage of water for 

 the construction of chart 3. 



•0 



15 



20 



24 



Chart 3 Showing the differences in the calculated water content of the brains 

 of the test rats compared with those of the control rats. 



It is evident at once that the relative water content in the 

 brain of the test rats is definitely higher during the first seven 

 hours, and then falls below that of the controls and reaches its 

 minimum at about nine hours, and so far as the present data are 

 concerned, the relative water content of the test brains again 

 rises, tending at the end of the period to approach the original 

 level. On account of the irregularities, it is not desirable to 

 place too much stress on the exact form of this graph; neverthe- 

 less, it gives unquestionable evidence of an increase in the water 

 content during the first seven hours, followed first by a sharp 

 fall and then by a return toward the normal or control value. 



