According to the conclusion on page 162, the purpose of this book is goiter prophylaxis. With two exceptions (and two translations) only German literature is quoted. On page 94 the analyses on one sample of blood are given, in micrograms per hundred cubic centimeters (γ%), as from 8.2 to 69.2. With 750 per cent error it is rather difficult to understand how small differences in the results of iodine analysis can be used for theoretical work. Furthermore, there is a peculiar method of using the analyses. The micrograms per hundred grams (7%) in thyroid, heart, lung, liver, kidney, muscle, brain, spleen and skin of a rat are added together and the total is found to be from 1,677 to 8,894 micrograms in the different experiments, and yet in one case the thyroid is said to contain only 721 micrograms. Just what these figures mean it is impossible from reading the