REGULATORS 597 



Reverdins in 1882 described a somewhat similar condition after 

 removal of the thyreoids in operations for goitre. In the last 

 decade of the nineteenth century the experimental investiga- 

 tion of the effects of removal was taken up. 



(1) Removal. — A difficulty is experienced in studying the 

 effects of removal, inasmuch as the parathyreoids lie embedded 

 in the thyreoid of most animals, and in close juxta-position to 

 it in others, and care is required to leave a sufficient amount of 

 these to carry on their functions. 



When proper precautions are taken, it is found that the 

 effect of removal of the thyreoid in young animals is to check 

 the growth, and especially to check the growth of cartilage 

 in developing bone (p. 46). This leads to marked shortening 

 of the long bones, causing stunted growth. The basis cranii is 

 also affected, and, since the intra-membranous bones continue 

 to grow, the frontal bones tend to arch forward. The gonads 

 do not develop, but remain infantile. The animal is generally 

 dull — lethargic. 



In adiclts the changes are less prominent. Muscular weak- 

 ness and apathy are marked. The hair falls out, and the tem- 

 perature is low. There is often a peculiar swelling of the skin, 

 which does not pit on pressure. The rate of metabolism is 

 markedly decreased. The mobilisation of carbohydrates is 

 lowered and the carbohydrate tolerance is raised. Removal of 

 the thyreoid decreases the glycosuria produced by removal of 

 the pancreas, and in this respect the influence of the thyreoid 

 co-operates with that of the chromaffin tissue in facilitating 

 the mobilisation of carbohydrates, which is held in check 

 by the pancreas. The functions of the sexual organs are 

 disturbed. The condition is sometimes known as cachexia 

 strumipriva. 



(2) Hypothyreoidism (Decreased Functional Activity). — (a) 

 In the young. — The thyreoid may be congenitally imperfectly 

 developed in man and animals, and all the conditions described 

 under the effects of removal of the gland are in a very marked 

 degree, (b) In the ad^dt human subject. — When the thyreoid 

 atrophies, the disease myxcedema is produced. The sufferer 

 manifests the symptoms described above as cachexia strumi- 

 priva. 



(3) Transplantation. — If, when the symptoms folloAving re- 



