| Popis: |
It has long been known that there is a marked variability in the antirachitic potency of cod liver oil; that for unexplained reasons oils of higher or lower potency are obtained at the same season of the year and even from fish in the same locality. The same is true in regard to vitamin A, as was brought out some years ago in a study by Zilva and Drummond. 1 As far as we are aware, the only livers of the cod which have been assayed for their antirachitic value have been those obtained in either the spring or the summer months— in other words at the time of the year when the livers are large and fat and yield the greatest amount of oil. When they are "poor," that is to say, small and lean, it has been taken for granted that they are unsuitable for the extraction of |
