Donaldson and Schoemaker, Absorption of Water. 189 



To explain Table I we need to analyze the record in the 

 first line only (Group I), as the construction of the other lines 

 is quite similar to it. 



Group I consists of 4 pairs of frogs — a pair being always 

 killed at one time and one frog dissected at once, while the 

 other was put aside ; in this case for 24 hours. In the first 

 column under body-weight m grams — extremes — is given the 

 weight of the lightest (16 grams) and the heaviest (18. i grms). 

 The average of the entire group of 8, appears in the next col- 

 umn as 17. 1 grams. From each of the four "control" frogs, 

 the spinal cord was removed between the limits previously 

 noted and the length of the cord measured to tenths of a milli- 

 meter. Taking now the sums of the weights of all the cords 

 and the sum of their lengths, we divide the former by the latter 

 and obtain the average weight for one standard millimeter of 

 cord. The same operation is repeated in the case of the spinal 

 cords of the "absorbing frogs" which had been allowed to lie 

 for 24 hours in the nearly closed vessel as above described. On 

 comparing each of the pairs for differences in the weight of 

 the standard millimeter, it was found, as shown in the last col- 

 umn, that in one pair the absorbing frog had gained only 5.3% 

 in weight, while in another pair the gain was 17.8. These were 

 the extremes. The average of all the four pairs was 13.5% as 

 given in the third column. Thus the numbers of most interest 

 are the average percentage gains in each case and the other 

 numbers given indicate the significance of these averages. Con- 

 sidering in turn the three groups, we see that Table I shows 

 that the average percentage increase in the weight of the cord 

 of the absorbing frog ranges from 13.5 to 25. i ^ and that in 

 the groups given in this Table, the average percentage increase 

 becomes greater as the average body weight of the frogs 

 increases. 



In comparing the effects of various conditions, therefore, 

 frogs of the same weight should be used. 



The conditions surrounding the frogs were next varied in 

 several ways in order to determine those under which the 

 absorbtion by the frog would be greatest. In Series II, the 



