942 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 



especially in the integument. These tissues become swollen and contain 

 a superabundance of inucin ; l the integument especially swells and the 

 eyelids become puffy, but at the same time the surface becomes dry, 

 and there is a tendency to the shedding of hairs and of the superficial 

 epithelium. This hyperplastic change is followed, if the animal remains 

 alive for a sufficient time, by atrophic changes. The nervous affection 

 which primarily results is usually accompanied by slight fever. Later 

 on this passes off, and the temperature becomes reduced even to some 

 degrees below normal. 2 



As Schiff originally showed, these effects of thyroidectomy can be 

 temporarily prevented by a graft of thyroid ; they may also be caused 

 to disappear either by injection of l^hyroid juice into a vein or under 

 the skin, 3 or even by taking thyroid juice or raw thyroid by the 

 mouth. The effects of grafts are to all intents and purposes permanent, 

 and it has been found, as in the case of the pancreas, that removal of 

 the graft which has maintained the health of the animal after extir- 

 pation of its own thyroid, is speedily followed as with primary removal 

 of the organ by the usual symptoms of thyroidectomy. It appears, 

 however, to be somewhat difficult to ensure the graft taking. 4 



Theories of action of thyroid extirpation. Various theories have 

 been advanced to account for the effects of removal of the gland. 

 H. Munk 5 held that the effects of removal are due, not to interference 

 with the functions of the gland, but to interference with adjoining 

 nervous structures in the neck. But this, as with the similar theory 

 propounded to account for the effects of extirpation of the pancreas, 

 is absolutely negatived if the results of thyroid grafting are to be 

 accepted. Besides this theory, two others, out of the many which have 

 been put forward, deserve consideration. 6 Of these the one may be 

 called the theory of " autotoxication " and the other that of " internal 

 secretion." The autotoxication theory assumes that there are one or 

 more toxic substances constantly tending to accumulate in the blood, 

 and which it is the purpose of the thyroid gland to remove and 



1 F. Semon (Brit. Med. Journ., London, 1883, vol. ii. p. 1073) has enunciated a theory 

 which deserves consideration here, to the effect that removal of the thyroid produces an 

 interference with the full chemical development of the constituents of the connective 

 tissues, so that these tend to take on an embryonic character ; and it is well known that 

 excess of mucin is characteristic of embryonic connective tissue. 



2 See on this subject, Horsley, Brit. Med. Journ., London, 1892 ; Ughetti, Riforma 

 fried., Roma, 1890, vol. vi. p. 228. 



3 Vassale, Riv. sper. di freniat., Reggio-Emilia, 1890, tome xvi. p. 439 (abstract in 

 Centralbl.f. d. med. Wissensch., Berlin, 1891, S. 14) ; and Arch. ital. de biol., Turin, 1892, 

 tome xvii. p. 173 ; Gley, Compt. rend. Soc. de biol., Paris, 1891, p. 251 ; G. R. Murray, 

 Brit. Med. Journ., London, 1891, vol. ii. p. 796; 1892, vol. ii. p. 449; 1893, vol. ii. p. 

 677 ; Schwarz, Sperimentale, Firenze, 1892, vol. xlvi. ; Arch. ital. de biol., Turin, tome 

 xvii. p. 330 ; Chopinet, Compt. rend. Soc. de Uol, Paris, 1892, p. 602 ; Brown-Sequard, 

 Arch, de physiol. norm, etpath., Paris, 1892. 



4 v. Eiselsberg, Wien. Idin. IVchnschr., 1892, S. 81. For a successful case of thyroid 

 grafting in the human subject, see Macpherson, Edin. Med. Journ., May 1892. 



5 Sitzungsb. d. Jc. Akad. d. Wissensch. zu Berlin, 1887, S. 823, and 1888, p. 1059. 

 See on the subject of Munk's experiments, and also on thyroid grafting, Halstead, Johns 

 Hopkins Hosp. Rep., Baltimore, 1896, p. 373. The bulk of this paper deals with the 

 hypertrophy of the remaining portion which follows the removal of a part only of the 

 thyroid. In a recent paper (Virchow's Archiv, 1897, Bd. cl. S. 271) Munk endeavours to 

 maintain his position. He denies that either cachexia or myxcedema necessarily follows 

 thyroidectomy, but in this he is at variance with nearly all other experimenters and with 

 the result of clinical experience. 



6 For older theories regarding the functions of the thyroid, see Horsley, Brit. Med. 

 Journ., London, 1892, vol. i. p. 267 et seq. 



