942 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 
especially in the integument. These tissues become swollen and contain 
a superabundance of mucin ; 1 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 thyroid 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. 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 
med., Roma, 1890, vol. vi. p. 228. 
3 Vassale, Riv. sper. di frcniat., Reggio-Emilia, 1890, tome xvi. p. 439 (abstract in 
Oentralbl. f. d. Tried. Wissenseh., 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 biol., Paris, 1892, p. 602; Brown-Sequard, 
Arch, de physiol. norm, et path., Paris, 1892. 
4 v. Eiselsberg, JVicn. klin. Wchnschr., 1892. S. 81. For a successful case of thyroid 
grafting in the human subject, see Macpherson, Edin. Med. Journ., May 1892. 
s Sitzungsb. d. k. Akad. d. Wissenseh. zu Berlin, 1887, S. 823, and 18S8, 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 {Virchows 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. 
