THE PITUITARY BODY 



action of anterior pituitary extract.'" Thyroid extract caused 

 no change in the metabolism of water either in thyroidecto- 

 mized or in hypophysectomized-thyroidectomized dogs. As a 

 result of their experiments in cats and rats, Dodds, Noble, 

 and Williams (1937) also suggested that the diuretic action 

 of anterior pituitary secretion after the removal of the pos- 

 terior lobe is not due to thyrotropic hormone. 



Evidence from other types of experiments speaks more in 

 favor of than against the belief that a secreting thyroid gland 

 is responsible to an important extent for the polyuria of dia- 

 betes insipidus. It is necessary also to bear in mind that the 

 importance of the thyroid gland may vary in different ani- 

 mals. Mahoney and Sheehan (1935) occluded the pituitary 

 stalk in dogs by means of a silver clip. The subsequent severe 

 polyuria and polydipsia could be abolished by thyroidectomy 

 and later re-established by the feeding of thyroid extract. 

 The removal of the thyroid in cats with diabetes insipidus 

 caused by a lesion of the supraoptico-hypophysial system 

 "may somewhat reduce but does not abolish the polyuria" 

 (Fisher and Ingram, 1936; Ingram and Fisher, 1937). On 

 the other hand, the feeding of thyroid to such cats causes a 

 marked diuresis; after the withdrawal of thyroid-medica- 

 tion, the polyuria may be as great as before thyroidectomy. 

 Findley and Heinbecker (1937) completely removed the thy- 

 roid from a man with syphilis of the central nervous system 

 and with diabetes insipidus. The important changes observed 

 subsequent to the operation were some reduction of the poly- 

 uria when the amount of salt in the diet was high or unre- 

 stricted and some increase in the diuresis-inhibiting effect 

 of "Pitressin" (see also Findley, 1937). 



4. Miscellaneous observations. — According to Pickford 

 (1936) as well as others, the action of posterior-lobe extract 

 after intravenous administration is, within certain limits, in- 

 versely proportional to the "water load" of the body. This 



'" The extract sometimes caused an initial decrease in the rate of formation of 

 urine. This always occurred in the monkey and might be the only change observed. 



I284] 



