98 HENRY H. DONALDSON 
TABLE 3 
Albino rat. Change in the percentage of water for each 0.001 gram of spinal cord 
weight as obtained from the comparison of the light and heavy cords in the same 
age group 
CORRECTION FACTORS 
PHASE AGE IN DAYS 
Males Females 
1 10-58 0.010 0.008 
2 58-365 0.009 0.007 
As noted in the case of the brain, neither the body weight nor 
the observed cord weight for the several age groups are given. 
These data, however, have been placed on file at The Wistar 
Institute. 
Application of the correction factors in the case of new data 
To obtain the corrected value for the percentage of water in 
the case of a new observation on the spinal cord, the same data 
are required as in the case of the brain (p. 88). The details 
are presented in following paragraphs: 
Body length is a more reliable guide than body weight. If 
we continue the illustration of procedure with the same case 
as that which was used for the brain (see p. 88) we have as 
data: body length 179 mm., age 173 days, female, cord weight 
0.458 gram, percentage of water 72.00 per cent. 
If we compare the observed value with that in table 74 for 
this age—173 days—it appears that the cord weight expected 
was 0.580 gram, or 0.122 gram in excess of the observed 
weight.. Using 0.007 as the correction factor for 1 mgm., the 
total correction amounts to 0.854 to be subtracted from 72 per 
cent, the observed water content, thus giving the final percent- 
age as 71.15 per cent. ‘Table 74 gives 70.22 per cent for this 
age, so that when tested in this manner the corrected value is 
about 1 per cent too high. We conclude in this instance, as we 
did previously, in the case of the brain, that the growth changes 
in the spinal cord of this rat had been somewhat retarded. 
