138 yournal of Comparative Neurology and Psychology. 



in Table 14 the percentage of water was determined in a group of 

 eight frogs (4 males and 4 females) and seventeen such records are 

 here reported. The body weight of the frogs in each group 

 was the same, that is, 25 grams, approximately. 



The range in the entire series here given is for the brain from 

 84.2 per cent to 86.2 per cent, and for the spinal cord from 78.8 

 per cent to 81.6 per cent, while the average of the four entries for 

 the month of August, is for the brain 85.1 per cent and for the 

 spinal cord 80.5 per cent. These are very close to the values for 

 the second and third groups of R. pipiens (with a body weight 

 near 25 grams) as given in Table 13. 



TABLE 14. 



Percentages of water in the brain and in the spinal cord of R. pipiens. Average 

 body weight is 25 grams. Each entry is based on a determination for eight 

 specimens (4 males and 4 females). From an unpublished study on the 

 influence of season made in 1901. 



Percentage Water in 



Date. 

 June 5. 



19- 

 26. 



July 



Aug. 



Sept. 



15- 



29. 



5- 



19- 

 26. 



9- 

 16. 



23 • 



It seems probable from this comparison that we have obtained 

 a generally correct value for the percentage of water in R. pipiens. 

 In the case of R. temporaria, the specimens were dried at Liver- 

 pool, but not weighed until I reached Zurich. There they were 

 further dried for 24 hours in the oven that was also used for drying 

 the R. esculenta material, and then were weighed. They were 

 found to give (see Table 13) the smallest percentages of water. 

 This naturally raised the question as to whether they had been 

 completely dried. The evidence that the drying was complete 

 is only indirect. It is as follows: 



