Chart 3.—Growth curves of Rats 7, 8, 9 and 10 on Rations 3, Casein, protein-free milk, and 4, Sanatogen, protein-free milk.
The difference in the gains in weight shown by the four rats are not great and certainly do not warrant the conclusion that Sanatogen possesses any marked superiority over the commercial casein in promoting growth. The slightly increased gains shown by Rats 9 and 10 are entirely incommensurate with the cost of the Sanatogen. All of the rats showed a vigorous growth and exceeded the average weight expected for rats of their respective ages, based on the long series of observations of Osborne and Mendel, as shown in Table 4.
TABLE 4.—WEIGHT OF RATS 7 TO 10 COMPARED WITH
AVERAGE WEIGHT OF RAT OF SAME AGE
| Rat | Age in Days | Final weight, gm. | Average Weight for rat of Same Age, gm. |
| 7 | 148 | 237 | 204 |
| 8 | 138 | 214 | 201 |
| 9 | 145 | 247 | 204 |
| 10 | 134 | 227 | 197 |
The results secured by Rations 5 and 6 compared with Rations 3 and 4, the only difference being that natural protein-free milk was used in the latter and artificial protein-free milk in the former, are most striking. Such results were anticipated from the experience of Osborne and Mendel in feeding similar materials. All of my rats, except Rat 13, a casein rat, showed a decided loss in weight after five weeks’ feeding on rations containing artificial protein-free milk. These losses amounted to 19.7, 9.0, 23.1, 6.7 and 27.6 gm., whereas rats fed on the same rations, except for the form of protein-free milk, gained, during the same period of five weeks, 56.3, 49.6, 57.8 and 59.1 gm. The fact that one casein rat fed on the artificial protein-free milk showed a substantial gain is without significance, as such exceptions to the general rule occur occasionally, and, furthermore, this rat also during the last week of the experiment likewise lost weight. The extent of these losses compared with what the average normal male rat weighs at a corresponding age is shown in Table 7.
TABLE 5.—WEIGHTS OF RATS FED RATION 5, CASEIN, ARTIFICIAL PROTEIN-FREE MILK*
| Date | Rat 11 | Rat 12 | Rat 13 | |||||||
| Weight, gm. | Gain or Loss, gm. | Weight, gm. | Gain or Loss, gm. | Weight, gm. | Gain or Loss, gm. | |||||
| 3/9 | 132.1 | ..... | 110.0 | ..... | 99 | .0 | ..... | |||
| 3/16 | 130.4 | -1 | .7 | 116.8 | +6 | .8 | 110 | .3 | +11 | .3 |
| 3/23 | 136.8 | +6 | .4 | 130.8 | +14 | .0 | 108 | .6 | -1 | .7 |
| 3/30 | 137.1 | +0 | .3 | 138.0 | +7 | .2 | 100 | .2 | -8 | .4 |
| 4/6 | 127.1 | -10 | .0 | 143.9 | +5 | .9 | 95 | .5 | -4 | .7 |
| 4/13 | 112.4 | -14 | .7 | 143.6 | -0 | .3 | 90 | .0 | -5 | .5 |
| Total | ..... | -19 | .7 | ..... | +33 | .6 | ..... | -9 | .0 | |
| 4/20 | 146.7 | +33 | .7 | 170.7 | +27 | .1 | 104 | .0 | +14 | .0 |
| * Date 4/20 covers use of mixed food. | ||||||||||
| Rat 13 suffered more or less from diarrhea throughout the whole experiment, and Rat 16 suffered similarly during the first two weeks. | ||||||||||