As mentioned in Chapter II, Loewy and Richter,[160] of Berlin, observed that removal of the sexual glands always produced a diminution of the oxidation processes. Footnote 160: Archiv für Anat. u. Physiol., Supplement, 1899; and Ergebnisse der Physiologie, ii, 1902. The experiments of Prof. Loewy and Prof. P. F. Richter are not invalidated, in our opinion, by the experiments of Lüthje, who did not find an increase in metabolism after ovarian feeding. The reason for this may be that he was not in possession of active extracts. Anyone who works with animal extracts knows what a great difference there is between various organo-therapeutical preparations, some being more efficacious than others. As a rule castrated animals take on fat, and this fact has for many years been made use of by farmers. At the same time the flesh of such animals acquires a better flavor, the pronounced flavor of the meat of non-castrated animals being objectionable to some consumers. This demonstrates the very instructive fact that the internal secretion of the testicles has its effect on all parts of the body. Castration in man is very frequently followed by obesity and symptoms of old age. Thus the eunuchs of eastern countries are very often fat and, at the same time, look much older. The influence of the ovaries upon fat formation can also be shown by their therapeutical action in obesity. Although not so active as thyroid extracts, we have found that by the combined use of thyroid and ovarian extracts, we could produce a considerable loss in weight, when, by thyroid treatment alone, we could not obtain it. This, however, is only in the case of women. We will treat of this subject more fully in the chapter on ovarian treatment. Besides the above-mentioned experimental facts, which show that these attributes of old age—obesity and increase of connective tissue—can be produced by removal of the thyroid or sexual glands, we also have to deal with facts gained by clinical observation, which show that any cause inimical to the ductless glands, especially the thyroid and ovaries, may bring about old age. Take, for example, infectious diseases. They have a very damaging effect on the various ductless glands, especially so if they are of long duration. Their influence upon the thyroid has been clearly shown by various observers. (Roger and Garnier, Crispino, Torri, Bayon, de Quervain, and others. See Chapter III.) Not only the thyroid gland, but other ductless glands, are affected by infectious diseases, and in the third chapter of this book we have shown that the adrenal glands show alterations indicating hyperactivity in infectious diseases. The pituitary gland is also altered in infections, as shown in the same chapter.