PITUITARY BODY 647 



disease connected with changes in the thyroid, but frequently with 

 another condition, called acromegaly, in which the bones of the 

 limbs and face, especially the hands and feet and the lower jaw, 

 become hypertrophied. JJ 



/Another condition often associated with tumours of the pituitary 

 is gigantism a condition occurring before the normal growth of 

 the bones is completed, and resulting in a great increase in the 

 length of the bones both in the limbs and the trunk.l 

 I Action of Intravenous Injection of E^racts of me Pituitary jf- 

 The effects on the vascular system of (intravenous injection of 

 extracts of the pituitary gland are also very different from those 

 caused by thyroid extracts. /(The posterior lobe,W infundibular 

 body, including the pars intermedia/contains two active substances, 

 one pressor and the other depressor.} The former is soluble in salt 

 solution, but insoluble in absolute alcohol and ether; while the 

 latter is soluble in sail solution as well as in alcohol and ether, jflhe 

 pressor substance lobtained in fairly pure form in the preparation 

 called pituitrin, and in still greater concentration in a preparation 

 to which the name hypophysin has been given)[causes a great rise 

 of blood-pressure, due partly to constriction on the arteriolew and 

 partly to an increase in the force of the heart-beat, both of which 

 are brought about by direct action. /This rise of pressure lasts for 

 a considerable timejand is sometimes accompanied by a slowing 

 of the heart. t A second dose injected before the effect of the first 

 has passed on is inactive : and this distinguishes the pituitary from 

 the suprarenal extract! I Associated with the pressor effect is an 

 increase in the flow of tne urinej Whether this is due to a separate 

 diuretic substance, as some maintain, has not been definitely settled. 

 /The pressor substance, unlike adrenalin, directly stimulates smooth 

 muscle fibres (especially the arteries, uterus, and spleen^ irrespective 

 of their innervation (Dale). Hypophysin has been employed to 

 stimulate the uterine contractions in obstetrical practice with 

 apparently satisfactory results. When injected intramuscularly, 

 regular and powerful contractions of the uterus are excited in two 

 or three minutes at any stage in parturition. fThe depressor sub- 

 stance produces a marked fall of blood-pressurel even when it is 

 injected during the rise of pressure caused by an injection of the 

 pressor substance. I The anterior lobe, or hypophysis, also contains 

 a depressor substance) Intravenous injection of a saline extract 

 causes a distinct falKof blood-pressure, accompanied usually by 

 acceleration and weakening of the heart (Fig. 207). A second in- 

 jection immediately following the first produces no change in the 

 pressure. But extracts of many organs, including the nervous 

 tissues, cause a similar fall of pressure, and there is no evidence 

 that the depressor substance of the anterior lobe is specific to the 

 pituitary (W. W. Hamburger). 



