Nov. 15, 19x5 Gossypol , the Toxic Substance in Cottonseed Meal 
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TOXICITY OF PRECIPITATED GOSSYPOE 
By the term “precipitated gossypol” we designate a product obtained 
from the gossypol extract. In securing the extract in larger quantities 
the oil was not entirely removed from the cottonseed kernels by several 
previous extractions with gasoline; hence, the gossypol extract contained 
considerable amounts of oil. The dark-red oily gossypol extract, after 
evaporation of the ethyl ether, was mixed with a large quantity of 
petroleum ether. Under some conditions a part of the gossypol precipi¬ 
tated in brown flocks, which could be separated easily by filtration. 
Under conditions of rapid precipitation these flocks would agglomerate 
and form a red resinous material. Both the light-brown powder and 
the red resinous material dissolved in ether very readily, giving a deep 
cherry-red solution. 
Another artificial cottonseed meal was prepared by dissolving weighed 
quantities of precipitated gossypol in ether, pouring the solution over 
corn meal, and warming over a steam bath to drive off the ether. One 
gm. of precipitated gossypol was usually mixed with 50 gm. of com 
meal. This proportion was based on the assumption that gossypol 
existed in cottonseed kernels to the extent of 2 per cent. 
Our earlier estimate of 2 per cent appears to be too high. The largest 
yields of crystalline gossypol acetate secured from the extract were from 
0.8 per cent to 1 per cent of the weight of the kernels. This probably 
represents nearly the entire amount present, as very little gossypol is 
dissolved by gasoline and little is left after ether extraction, judging by 
the slight toxicity of the residue. 
Pouring the deep cherry-red solution over corn meal gave it a red 
color. When this was warmed over the steam bath, the color of the 
corn meal changed to a typical cottonseed-meal yellowish brown. No 
explanation is offered for this change; but it is evidently not due to 
oxidation, as the change begins at the bottom of the mixture, not at 
the surface. 
This artificial meal was fed to six rabbits and proved fatal in every 
case. We had difficulty in getting them to eat it after having been once 
made sick. 
Rabbit 954 was taken from feed 318 (gossypol extract) and offered 
com meal and molasses containing 0.37 gm. of precipitated gossypol. 
It ate an equivalent of 0.3 gm. of the precipitated gossypol by the second 
day and seemed slightly indisposed. A week later it was again put on 
this feed, at the rate of 0.2 gm. daily. The quantity of gossypol eaten in 
the first six days was, per day, 0.2, 0.2, 0.17, 0.10, o, and 0.05 gm. It 
ate none after this, but became sicker and died six days later. 
Rabbit 961 ate 0.9 gm. of precipitated gossypol mixed with corn meal 
and molasses. It was apparently normal the next day, but refused 
cabbage on the third day. Thereafter it ate green feed well, but seemed 
to have no appetite for corn meal and molasses except when very hungry. 
