_Thymus gland_ feeding has also been reported on favorably by a number of observers (Rohdenburg, Bullock, and Johnson, also Gwyer), they reporting relief of pain and improved general conditions, notably gain in weight and increased hæmoglobin in all but one of sixteen cases, though some of them died. On the other hand Ross reports most unfavorably on the administration of thymus, which he gave to some inoperable and hopeless cancer cases, in which he said that in two or three weeks the tumors had quadrupled in size and the condition of the patients was very much worse; the same occurred also when some cancer patients were given calcium salts freely. Ross makes some interesting suggestions in regard to the thymus, and its relation to calcium and magnesium; these latter are freely utilized in the growth of bone up to the age of twenty-five years, by which time the thymus gland has quite disappeared; but after this time these salts tend to have pathological relations in various tissues, and also cancer becomes frequent. The internal secretions of the _testicles_ and _ovaries_ are also thought to have some share in metabolic processes, and observations have been made in regard to their influence in cancer. Thus Cahen reported that Beatson’s operation of castration for cancer, done first in 1896, had been repeated by many, so that Lott had reported 99 cases including his own. Of these in 23.2 per cent. the operation caused a distinct improvement in the cancer. In 15 cases the improvement persisted for a year, in 4 cases for 4½ years and in one case for over 5 years. Cahen operated on seven women with remarkable results; in two cases life was prolonged 4 and 6 years respectively. Others, however, have shown by statistics, that damage to the ovaries by disease, or their removal by operation, greatly increases the proclivity to cancer. Several writers have connected cancer with the waning of the sexual powers, and the suggestion is made by Sherrington and Copeman that in the period which antedates the cancer age, the reproductive glands, by means of internal secretions, are able to inhibit the growth of cancer. In looking back over what has been observed in regard to the secretions, including those of ductless glands, we see that very strong evidence has accumulated to show that they have a very intimate connection with the development of cancer, as was to be expected, since they are very important factors in connection with metabolism.