418 Pellagra-Producing Diets. V 
standard mixture and failed to grow. In Period 2 the content of _ 
the fat-soluble A was increased by the addition of butter fat, 
but without noticeable benefit. Chart 1, Lot 1,916 A, showed 
that the addition of an appropriate inorganic salt mixture, and 
Lot 1,915 an addition of purified protein did not supplement the 
mixture of peas, patent flour, and cottonseed oil so as to induce 
growth. Two purified food additions, one of which is inorganic, 
are necessary (Chart 3, Lots 1,022 and 1,023). These rats (Lot 
1,916 B) showed the same skin lesions on the nose, ears, and tails 
that were described in Chart 1, Lot 1,915. They differed from the 
latter in being extraordinarily irritable. They were terror 
stricken whenever the cage door was opened, and there was always 
great difficulty in weighing them. Irritability in some degree 
was characteristic of all the rats on this ration where but one 
purified food addition was made. Extreme timidity is of com- 
mon occurrence in our experimental rats on certain types of faulty 
diet. We are not yet in a position to discuss satisfactorily the . 
exact nature of the causes of this abnormality. 
Lot 1,021.—These records illustrate the fact, when interpreted 
together with Chart 3, that both protein and fat-soluble A (as 
butter fat) added to the diet of Period 1 fail to make the ration 
capable of supporting growth. The addition of certain salts 
(sodium, chlorine, and calcium) is necessary before growth can 
proceed. These salts alone are, however, not sufficient (Chart 
1, Lot 1,916 A). Either the protein must be improved,.or the 
fat-soluble A must be increased in amount, as well as an im- 
provement in the inorganic moiety effected before the food mix- 
ture becomes capable of supporting growth (Chart 3, Lots 1,022 
and 1,023). It is not apparent from the curves of growth that it 
is of great importance for some weeks whether the second factor 
which is improved. is protein or fat-soluble A. Growth can take 
place in either case. Prolonged well-being requires, however, in 
addition to other supplements, an increase in the content of fat- 
soluble A in this food mixture. 
Chart 3. Lot 1,022.—In Period 1 the animals were fed the 
standard mixture of peas, patent flour, and cottonseed oil and 
were unable to grow. In Period 2, the addition of two purified 
food substances, the simple salt mixture of sodium chloride and 
calcium carbonate, together with purified casein, induced prompt 
