Abstract
On August 2, 1923, we began two independent series of feeding experiments on albino rats (in tests continued through successive generations), to determine whether or not Intarvin, added to an ordinary balanced laboratory diet, in quantities ranging from five to twelve per cent of the total daily food intake, would induce any evidences of toxicity.
Eight normal female rats from one litter were originally separated into groups of four. One of two males, of practically the same size and vigor from an unrelated litter, was added to each of these two groups. One group received a balanced natural diet with a definite proportion of Intarvin mixed with the meat ration. The other group received the same natural diet under identical conditions, with rendered lamb fat instead of Intarvin added to it. In each successive generation, thereafter, the maternal rats that received Intarvin were selected from the direct descendants of those that had previously been given the “intarvinated” diet. The control maternal rats in each generation in a series were selected from the direct descendants of those that received a diet containing an addition of lamb fat. The paternal rats in each generation (unrelated to the females) were selected on the same dietary basis as that for the maternal, or from litters on the ordinary diet without addition of fatty matter.
Rats have been carried, in this parallel way, into the fourth generation in one series and into the third generation in another. (The experiments are in progress; and litters in the fifth and fourth generations, respectively, will soon be available.) There has been no discernible effect on the animals thus treated, or on their fecundity. The animals in the third and fourth generations appear to be as completely normal as those with which the tests were started last August.
Get full access to this article
View all access options for this article.