430 
Journal of Agricultural Research 
Vol. XIV, No. 10 
EXPERIMENTAL WORK 
EXPERIMENTS WITH RATS 
On cottonseed meals which contain no unchanged gossypol, but 
apparently only the D-gossypol, rats have not done so well as on ether- 
extracted raw kernels which contain no D-gossypol and only traces of 
unextracted gossypol. (See Table I, diets 390, 392, 393, 383, and 
383A; see also fig. 2, 3.) This fact leads us to maintain that there is 
still a toxic factor in well-cooked cottonseed meals. The difference 
holds true of the restricted cottonseed diets, which are practically iden¬ 
tical with respect to protein, minerals, and vitamines. When these 
products are supplemented with 17 per cent of milk powder, there is no 
Fig. 2.—Graphs showing the toxicity of various diets to rats. Thoroughly cooked cottonseed products, 
diets 390 and 399, are inferior to ether-extracted raw kernels, diet 393, in restricted diets, apparently 
because there remains a quantity of a moderately toxic substance, D-gossypol, in the cooked products. 
This difference is not as noticeable in diets supplemented with milk powder or with certain mineral 
salts and butter fat. All these diets finally led to absolute failure. 
visible difference; in fact, such diets appear as efficient as the control milk 
diet for rats. In this respect our results agree with those of Osborne and 
Mendel (8) and Richardson and Green (jo, xj, 12). 
The rats used were bought from a dealer and were apparently in¬ 
ferior animals both in size and vitality. Few of them exceeded 200 gm. 
in weight, and many ceased growing at 100 to 125 gm. In the experi¬ 
ments animals from the same shipment were used in one set so that the 
results are generally but not always comparable with the results of 
other sets. In only one case out of many experiments with rats on 
unsupplemented cottonseed meal (long-cooked) diets have our rats 
shown appreciable growth. This instance (feed 390, lot 5) was with 
two rats from a litter reared in our animal rooms. The mother and 
young were fed on the control milk diet with occasional green food until 
