880 PHYSIOLOGY OF DIGESTION AND SECRETION. 



seems to be well established, but satisfactory proof is lacking for 

 the view that the posterior lobe secretes normally a hormone 

 having this action. In clinical cases in which there is reason to 

 believe that a deficiency of function exists in the hypophysis, a 

 condition of so-called hypopituitarism, as, for example, in brain 

 tumors affecting the hypophysis, one of the frequent symptoms 

 described is diabetes insipidus, a condition characterized by ex- 

 cessive secretion of urine and great thirst. It is difficult to recon- 

 cile this result with the view that the gland forms a diuretic hor- 

 mone, especially as in these cases of diabetes insipidus adminis- 

 tration of preparations of the posterior lobe is said to diminish the 

 polyuria. Evidently the relations, if any, of the posterior lobe to 

 the urinary secretion cannot be explained on the basis of our 

 present imperfect knowledge. Lastly, these extracts influence the 

 general metabolism, particularly in regard to the carbohydrates. 

 Like the epinephrin, they cause a glycosuria, and apparently in the 

 same way, that is, by accelerating the process of glycogenolysis in 

 the liver. 



Extracts of the Anterior Lobe. — In marked contrast to the effects 

 obtained from the posterior lobe, extracts of the anterior lobe when 

 injected yield no immediate results. As will be seen below this 

 lobe undoubtedly furnishes an important secretion, but the specific 

 action of this secretion is not revealed by the method of injection. 

 Robertson has isolated a substance from this lobe which he desig- 

 nates as tethelin. It contains nitrogen and phosphorus in the 

 ratio of 4 to 1, and is soluble in alcohol, ether, and chloroform, 

 although it may be precipitated from alcoholic solution by the 

 addition of ether. The author states that administration of this 

 material to mice, like the use of extracts of the entire lobe, has 

 a stimulating effect on growth. 



Removal of the Pituitary Body. — Very contradictory reports 

 were made by the earlier observers upon the result of the complete 

 removal of the pituitary body, but since the work of Paulesco it 

 has been generally accepted that hypophysectomy is essentially a 

 fatal operation. ♦ The animal dies in a few days after exhibiting 

 a series of premonitory symptoms, such as a fall in temperature, 

 unsteady gait, rapid emaciation, and diarrhea. Further examina- 

 tion has shown that this fatal outcome happens when the anterior 

 lobe alone is removed, and we may conclude, therefore, that the 

 secretion of this gland exercises some profoundly important influ- 

 ence upon metabolism, although the nature of this influence is not 

 as yet understood. Removal of the posterior lobe alone is not 



* See Gushing, "The Pituitary Body and Its Disorders," 1912; also Goetsch, 

 "The Quarterly Journal of Medicine," January, 1914. 



