206 
Journal of Agricultural Research 
Vol. XXXI, No. 3 
Figure 1. The first two groups of rats, Nos. 204 and 222, respectively, 
made slightly more growth than the three other groups, and this is 
probably due to the presence of a small amount of vitamin A in the two 
lots of purified ox muscle fed the first two groups of rats. The growth 
made by the rats in the last three groups, Nos. 234, 297, and 343, rep¬ 
resents about as good results as the writers have been able to obtain 
after having tested a considerable number more of highly purified 
basal rations. This indicates that the slight growth made by the 
i> 
S./ 
—w 
S' 
—i 
t 
297. 
_ ! 
> 
1 _ 
297B 
297 7 
297< 
0 
80 
60 
40 
20 
Fig. 1 .—Basal rations. Graphs showing rate of growth of five groups of rats, each group being fed a basal 
ration practically free from vitamin A but otherwise adequate. The rations fed to the first four groups 
of rats, including animals Nos. 204 A to 297 D, were made up in parts by weight as follows: Ox muscle 
treated to remove vitamin A, to make 20 parts protein; dried baker's yeast, 10; ash mixture, 4; hardened 
cottonseed oil sufficient to make 10 parts fat; and cassava starch to make 100. A different lot of ox muscle 
was used in each of the rations 
The ration fed to rats 343 A to 343 D, inclusive, was made up in the same proportions, except that 
casein, treated to destroy vitamin A, was substituted for ox muscle 
• The sex of each rat is indicated by the letter at the end of each graph, m denoting male, /, female 
last three groups of rats shown in Figure 1 was probably due to the 
reserve store of vitamin A in the tissues of the young rats, and that 
the growth made by the first two group's of rats was due chiefly to 
the same factor. 
Ophthalmia developed in most of the rats, as indicated, but it is 
not the writers’ practice to continue a feeding test for any consider¬ 
able time after a rat ceases to gain in weight even though oph¬ 
thalmia is not evident. 
A 
C343 
343 
C 
343 
