September 6, 1912] 



SCIENCE 



307 



tivity of the nervous system is well ascer- 

 tained. The form of idiocy known as 

 cretinism and the affection termed myx- 

 (Dedema are both associated with deficiency 

 of its secretion: somewhat similar condi- 

 tions to these are produced by the surgical 

 removal of the gland. The symptoms are 

 alleviated or cured by the administration 

 of its juice. On the other hand, enlarge- 

 ment of tha thyroid, accompanied by in- 

 crease of its secretion, produces symptoms 

 of nervous excitation, and similar symp- 

 toms are caused by excessive administra- 

 tion of the glandular substance by the 

 mouth. From these observations it is in- 

 ferred that the juice contains hormones 

 which help to regulate the nutrition of the 

 body and serve to stimulate the nervous 

 system, for the higher functions of which 

 they appear to be essential. To quote M. 

 Gley, to whose researches we owe much of 

 our knowledge regarding the functions of 

 this organ : "La genese et I'exercice des plus 

 hautes facultes de I'homme sont condi- 

 tionnes par Paction purement chimique 

 d'un produit de secretion. Que les psycho- 

 logues meditent ces f aits ! ' ' 



The case of the parathyroid glandules is 

 still more remarkable. These organs were 

 discovered by Sandstrom in 1880. They 

 are four minute bodies, each no larger than 

 a pin's head, imbedded in the thyroid. 

 Small as they are, their internal secretion 

 possesses hormones which exert a powerful 

 influence upon the nervous system. If they 

 are completely removed, a complex of 

 symptoms, technically known as "tetany," 

 is liable to occur, which is always serious 

 and may be fatal. Like the hormones of 

 the thyroid itself, therefore, those of the 

 parathyroids produce effects upon the 

 nervous system, to which they are carried 

 by the blood; although the effects are of 

 a different kind. 



Another internally secreting gland which 



has evoked considerable interest during the 

 last few years is the pituitary body. This 

 is a small structure no larger than a cob- 

 nut attached to the base of the brain. It 

 is mainly composed of glandular cells. Its 

 removal has been found (by most ob- 

 servers) to be fatal — often within two or 

 three days. Its hypertrophy, when occur- 

 ring during the general growth of the body, 

 is attended by an undue development of 

 the skeleton, so that the stature tends to 

 assume gigantic proportions. When the 

 hypertrophy occurs after growth is com- 

 pleted, the extremities — viz., the hands and 

 feet, and the bones of the face — are mainly 

 affected; hence the condition has been 

 termed "acromegaly" (enlargement of ex- 

 tremities). The association of this condi- 

 tion with affections of the pituitary was 

 pointed out in 1885 by a distinguished 

 French physician. Dr. Pierre Marie. Both 

 "giants" and "acromegalists" are almost 

 invariably found to have an enlarged 

 pituitary. The enlargement is generally 

 confined to one part — the anterior lobe 

 — and we conclude that this produces 

 hormones which stimulate the gro'«i;h 

 of the body generally and of the skeleton in 

 particular. The remainder of the pitui- 

 tary is different in structure from the ante- 

 rior lobe and has a different function. 

 From it hormones can be extracted which, 

 like those of the suprarenal capsule, al- 

 though not exactly in the same manner, 

 influence the contraction of the heart and 

 arteries. Its extracts are also instrumental 

 in promoting the secretion of certain 

 glands. When injected into the blood they 

 cause a free secretion of water from the 

 kidneys and of milk from the mammary 

 glands, neither of which organs are directly 

 influenced (as most other glands are) 

 through the nervous system. Doubtless 

 under natural conditions these organs are 

 stimulated to activity by hormones which 



