sept, a, 1918 Comparative Toxicity of Cottonseed Products 
427 
“home-made” products of Osborne and Mendel do not resemble mill 
products. For example, their raw kernels “subjected to vigorous 
treatment with live steam from one to six hours,” in which there was 
some loss through distillation and spraying, underwent a change in 
toxicity much more slowly than in the commercial process. In par¬ 
ticular, their laboratory treatment of the kernels made the mass so 
wet that it had to be dried before feeding. This is not the condition 
in the oil mill, where air is often drawn through the cooking drum to 
remove excess moisture. Under mill conditions the kernels undergo 
a much more rapid reduction in toxicity, for we have found oil-mill 
samples after 25 to 28 minutes’ cooking not markedly injurious? to 
rats in adequate diets, while Osborne and Mendel’s (8) product 
cooked for one hour was found by them to be appreciably toxic. 
After four hours’ cooking under laboratory conditions their product 
became less suitable for nutrition, and the results led them to assume 
that undue heating might render the meal unpalatable. This also 
seems to us unlikely to happen in the better regulated conditions of 
moisture and heating in the industry. 
Another point of marked difference is the fact that their actually 
cold-pressed oil was nontoxic, whereas we have found that the com¬ 
mercial so-called cold-pressed 1 oil is highly toxic because most of the 
gossypol from the resin glands has been dissolved by the oil and 
squeezed out unchanged. 
Our experiments (16) with raw kernels and gossypol led us to 
believe that gossypol is the only toxic substance in the raw cottonseed. 
The toxicity of the cottonseed meal varies with the amount of 
unchanged gossypol present. But from certain meals which we 
found definitely injurious to rabbits and swine no gossypol could be 
isolated by our methods. Apparently it had been entirely changed 
in the cooking process to a very similar substance, called by us 
“ D-gossypol,” which is much less toxic but which can not be regarded 
as being without physiological action. 
In the milling of cottonseed the decorticated kernels are cooked in 
steam-jacketed drums while being continually stirred with huge 
paddles. The mass becomes somewhat moist as the temperature 
rises, either from moisture present in the seed or from steam sprayed 
in, if the seeds are too dry. In this condition the kernels are quickly 
comminuted. These conditions are favorable for effecting an 
important change in the gossypol which issues from the glands and 
then spreads over the surface of the seed particles. The nature of 
1 The “cold-pressed" meal is made from kernels passed through preheaters surrounded by steam under 
pressure. This serves to drive out the moisture. The dried kernels are then ground in a screw press to 
express the oil. This also develops much heat from friction. The actual temperatures used in the hot 
pressing and cold pressing do not differ greatly. The latter is really a dry pressing rather than a moist 
pressing. 
