778 PHYSIOLOGY OF DIGESTION AND SECRETION. 



of two parts, a large anterior lobe of distinct glandular structure 

 and a much smaller posterior lobe whose structure is not clearly 

 known. The cells are said to form follicles which contain some 

 colloid material.* Embryologically the two lobes are entirely dis- 

 tinct. The anterior lobe, which may be designated as the hypoph- 

 ysis cerebri, arises from the epithelium of the mouth, while the 

 posterior lobe, or the infundibular body, develops as an outgrowth 

 from the infundibulum of the brain, and in the adult remains con- 

 nected with this portion of the brain by a long stalk. Howell f and 

 others have shown that extracts of the hypophysis when injected 

 intravenously have little or no physiological effect, while extracts 

 of the infundibular body, on the contrary, cause a marked rise of 

 blood-pressure and slowing of the heart beat. These effects resemble 

 in general those obtained from adrenal extracts, but differ in some 

 details. They seem to warrant the conclusion that the infundib- 

 ular body is not a mere rudimentary organ, as has been generally 

 assumed, but produces a peculiar substance, an internal secretion, 

 that may have a distinct physiological value. A number of ob- 

 servers, especially Vassale and Sacchi, have succeeded in remov- 

 ing the entire pituitary body. They report that the operation 

 results eventually in the death of the animal with a certain group 

 of symptoms, such as muscular tremors and spasms, apathy and 

 dyspnea, that resemble the results of thyroidectomy. It has been 

 suggested, therefore, that the pituitary body may be related in 

 function to the thyroids and may be able to assume vicariously 

 the functions of the latter after thyroidectomy. There is no satis- 

 factory evidence, however, in support of this view. On the patho- 

 logical side it has been shown that usually lesions of the pituitary 

 body, particularly of the hypophysis, are associated with a peculiar 

 disease known as acromegaly, the most prominent symptom of 

 which is a marked hypertrophy of the bones of the extremities and 

 of the face. The conclusion sometimes drawn from this fact that 

 acromegaly is caused by a disturbance of the functions of the pitu- 

 itary body is, however, very uncertain, and is not supported by any 

 definite clinical or experimental facts. 



Testis and Ovary. Some of the earliest work upon the effect 

 of the internal secretions of the glands was done upon the repro- 

 ductive glands, especially the testis, by Brown-Sequard.J Ac- 

 cording to this observer, extracts of the fresh testis when injected 

 under the skin or into the blood may have a remarkable influence 

 upon the nervous system. Mental and physical vigor, and the 



* Thorn, "Archiv f. mik. Anat.," 57, 632, 1901. 



t " Journal of Experimental Medicine, " 3, 245, 1898 ; also Schaefer and 

 Vincent, " Journal of Physiology, " 25, 87, 1899. 



J " Archives de physiologic normale et pathologique, " 1889-92. 



