688 HENRY H. DONALDSON 
They show that the rate is such as to cause the body weight to 
double, or more than double, from season to season during the 
three successive annual intervals; a very peculiar interesting re- 
sult when compared with the growth of mammals. 
Having thus determined the growth in body weight from season 
to season, it is desirable to calculate the weights of the central 
nervous system which correspond to the body weights found. 
We shall take but one instance—namely the last pair from the 
table 14—as these represent records for which we have some 
control observations. 
The weight of the central nervous system is determined by the 
formula based on body weight and body length, using in the first 
instance 20.2 for the value of C. This value of C was obtained 
in the following manner. On referring to table 9, page 681, it is 
seen that the value of C for R. temporaria on July 1, 1904, was 22.8. 
According to our present view of seasonal change, we should expect 
this to be the maximum annual value of C. If this be correct, then 
this value is 13 per cent greater than it would be in the spring or 
autumn; therefore at the two ends of the season we should expect 
the value of C to be 13 per cent less or 20.2. The weight of the 
central nervous system is therefore calculated accordingly, 7.e., 
with C = 20.2 for the two ends of the season. 
In addition to the two sets of values giving the body weight, 
total length and weight of central nervous system, first at the 
time of emergence of a given individual, and second at the time of 
its hibernation, there have been interpolatéd in table 15 the val- 
ues for this same frog when half grown in body weight—that is 
weighing 15.0 gms., and in the first instance the weight of the 
central nervous system in this half grown frog is calculated using 
20.2 as the value of C. 
This table 15 gives us a notion of what would take place. if the 
frog increased by about two and a half times its initial weight in 
the course of the season, and at the same time underwent the nor- 
mal correlated increase in body length and in the weight of its 
central nervous system—the relative weight of this latter remain- 
ing the same, 7.e., the constant C remaining unaltered during the 
process and having the value of 20.2. From the Zirich series we 
have reason to think, (see table 9,) that the mid season value of 
