Effects of External Conditions 135 
two lots. None of these differences except those in the length of 
the tail and foot are to be regarded as having any significance. 
Fig. 11. Series of 1907-1908: tail length of 
females at 7 months of age (based upon meas- 
urements after death—see text.) 
Fig. 12 Series of 1907-1908: foot length of 
emales at 7 months of age. 
Comparing:the measurements for this age with those (weight and 
tail) made%upon these same mice?® when 24 months old, we find 
79 Six of the warm-room lot and three of the cold-room lot had died in the meantime. 
