244 SCIENCE PROGRESS 



In 1*48, Claude Bernard demonstrated the possibilities of 

 internal secretion in the case of the liver, but he applied the 

 term " internal secretion " in a wider sense than it is held 

 to-day. The modern conception owes its origin to Brown 

 S^quard (1891), who limited the term to the secretion of specific 

 substances whose influence was necessary to the well-being of 

 the organism. Although nothing new was learnt regarding 

 the thyroid, this doctrine inspired and guided the experiments 

 which were subsequently undertaken to elucidate its function. 

 The earlier experiments, however, were largely prompted by 

 observations on individuals suffering from disease of the gland. 



The first serious attempt at experimentation was under- 

 taken by Schiff (1856). He removed the thyroids of various 

 animals, but, as his observations were incomplete, little atten- 

 tion was paid to them. At a later date (1884) he was encour- 

 aged by the work of the Reverdins (1883), on the removal of 

 goitres in human beings, to renew his former experiments on 

 a larger scale. He found that dogs and cats died shortly 

 after the operation, but that rabbits and rats survived. These 

 results drew the attention of physiologists to the importance 

 of the thyroid, and stimulated research in this direction. 



Since 1884, not only have numerous investigators con- 

 firmed and added to Schiff's work, but a vast literature, re- 

 quiring an encyclopaedic compilation, has come into being. 

 A brief sketch of the more important results is all that may 

 be attempted here, and for clearness the subject will be de- 

 scribed under the headings given below. 



The Effects of Diminished Secretion : Hypothyroidism. — ^This 

 condition may be brought about either by disease of the gland 

 or by operative interference. 



In the condition in children known as Cretinism, the gland 

 is atrophied or perhaps has never properly developed since 

 birth. Symptoms do not appear until the child is weaned, 

 presumably because sufficient thyroid material can be obtained 

 from the mother in suckling. The signs appear slowly, for 

 they are not new phenomena, but the non-appearance of 

 changes which one expects to find in a growing child. Years 

 may pass, and the cretin — for such it is by this time — has still 

 the appearance and bearing of an infant. It is short in stature 

 and stodgy, with podgy hands and feet and a pendulous belly. 

 Ossification remains incomplete, and the fontanelles persist. 

 The skin (likewise mucous membranes) is dry and almost hair- 

 less, especially the scalp, the muscles are flabby, and the ex- 

 ternal genitals are undeveloped. Want of intelligence portrays 

 the non-development of the nervous system, the cretin often 

 being a deaf-mute, imbecile, or idiot. The condition is, in short, 

 one of complete arrested development, and almost the same 



