SECRETION OF THE DUCTLESS GLANDS. 873 



mic goiter (Graves' disease). The anatomical facts in regard to 

 the involution of the gland after puberty justify the suggestion 

 that the function it exercises is of especial importance in the period 

 preceding the maturation of the sexual glands, but that in post- 

 pubertal life it continues to play some role, although of subordinate 

 importance. Very many experiments have been made to deter- 

 mine the nature of the function of this tissue, but at present it is 

 not possible to interpret the results in a satisfactory manner.* 

 Removal of the gland in young dogs (Basch) is said to cause a 

 retarded growth of the bony tissues and to induce a condition re- 

 sembling rickets. At the same time the peripheral nervous sys- 

 tem shows an increased excitability as determined by the response 

 of the nerves to galvanic stimulation. Somewhat similar but more 

 extensive experiments have been reported by Klose and Vogt. 

 When thymectomy is performed on quite young dogs (10 days), 

 very serious consequences result, ending perhaps in a condition of 

 coma and death. These results develop slowly: there is first a 

 stage of increased fat formation and later one of malnutrition or 

 cachexia which manifests itself strikingly in an atrophic and 

 undeveloped condition of the bones, although there is besides a 

 general asthenic or adynamic condition and mental deterioration. 

 Injections of extract of the gland (Svehla) cause a fall of blood- 

 pressure and some quickening of the heart-beat, but these effects 

 are not specific. Unlike the thyroid and parathyroid glands, the 

 thymus contains no iodin (Mendel) . One suggestion made regard- 

 ing its influence is that there is some sort of reciprocal relationship 

 between it and the reproductive glands. Castration (Henderson) 

 causes a persistent growth and retarded atrophy of the thymus, 

 while removal of the thymus (Paton) hastens the development of 

 the testes. Another more specific hypothesis is the one advo- 

 cated by Klose and Vogt in the work referred to above, namely, 

 that the thymus is concerned especially in the processes of syn- 

 thesis of nucleic acid. 



Gudernatsch f finds that young tadpoles fed upon thymus gland 

 are stimulated to excessive growth, while the changes of meta- 

 morphosis to the frog-stage are correspondingly delayed. When 

 thyroid gland is fed, contrary results are obtained. Further 

 growth is inhibited and the changes of metamorphosis are acceler- 

 ated, so that dwarf frogs are produced. This apparently direct 



* References: Friedleben, "Die Physiologic der Thymusdriise," 1858; 

 Verdun, "Derives branchiaux chez les vertebres," 1898; Henderson, "Journal 

 of Physiology," 1904, xxxi., 222; Basch, "Jahrbuch f. Kinderheilkunde," 64, 

 1906, and 68, 1908; Klose and Vogt, "Klinik u. Biologic d. Thymusdriise," 

 Tubingen, 1910; Halsted, "Johns Hopkins Hospital Bulletin," August, 1914; 

 Hart, "Virchow's Archiv," 214, 1, 1913. 



t Gudernatsch, "Zentralblatt fur Physiologic," 1912, No. 7. 



