=====================+=======+====+=======+======+=======+=== Female | A | B | C | D | E | F ---------------------+-------+----+-------+------+-------+--- _P. truei_ (A) | 447 | 17 | 33.00 | .796 | 26.29 | 3 _P. truei_ (B) | 676 | 28 | 32.70 | .738 | 24.14 | 3 _P. maniculatus_ (C) | 191 | 10 | 19.45 | .983 | 19.10 | 5 _P. maniculatus_ (D) | 133 | 14 | 24.35 | .224 | 5.46 | 6 ---------------------+-------+----+-------+------+-------+--- Female | G | B | C | H | I | F ---------------------+-------+----+-------+------+-------+--- _P. truei_ (A) | 214.7 | 26 | 33.00 | .250 | 8.26 | 3 _P. truei_ (B) | 120.5 | 24 | 32.70 | .153 | 5.02 | 3 _P. maniculatus_ (C) | 47.8 | 10 | 19.45 | .246 | 4.78 | 5 _P. maniculatus_ (D) | 180.1 | 21 | 27.42 | .312 | 8.58 | 6 ---------------------+-------+----+-------+------+-------+--- It is interesting that the female of _P. maniculatus_ with litter C used much more than the average amount of water for the species, and even more per gram of body weight than lactating females of _P. truei_. Conversely, water consumption of the female with litter D was within one standard deviation of the mean for all adults of _P. maniculatus_. I infer that at least some lactating females of _P. maniculatus_ are better adapted to aridity than are some lactating females of _P. truei_. Table 11 also shows food consumption of the four females discussed above. All females, with the exception of the female with litter D, consumed amounts of food that lie within one standard deviation of the means for their species. The female with litter D had the most young, consumed the most food but drank the least water of the four females. Later, when separated from her litter and placed on the low protein diet, this female drank only .046 milliliters of water per gram of body weight per day. This figure is less than one-third of the average amount (.174) for this species (Table 7). The records of water and food consumption for litters A, C, and D are given in Table 12; the mice in litter B persisted in placing wood shavings in the opening of the spout on their water bottle, causing loss of the water. The data show that mice in all three litters had an average water and food consumption within one standard deviation of the mean for adults of their respective species (Tables 7 and 12). It is interesting that juveniles of both species require no more food and water per gram of body weight than adults. This indicates that if a young animal survives the rigors of postnatal life until it is weaned, it is then at no disadvantage as far as food and water consumption are concerned. This would be greatly advantageous to the species, as a population, for the young could disperse immediately upon weaning, and go into any areas that would be habitable for adults of the species.