THE PITUITARY 351 



vagus, 1 and that fluid from the thyroid appears to increase the 

 excitability both of the vagus and the depressor, led to an 

 investigation of the action of these and other tissue extracts 

 upon the vasomotor reflexes. 



The extract of the pituitary body, sold under different names 

 by different firms, appears to convert a depressor reflex into a 

 pressor, or very considerably to exaggerate the pressor effect. 

 The latter effect is, in some cases, much more marked after 

 previous administration of adrenin. This action of pituitary 

 extract occurs only on a first injection. 



Brisk kneading of the intestines evokes normally a very 

 distinct vasomotor response, which is frequently accompanied 

 by a slowing of the heart-beat. The effect upon the heart is 

 very noticeable after the administration of pituitary extract, 

 and the beat is frequently of a grouped character. 



3. Effects on the Respiration 



Mummery and Legge have noted a diminution of the ampli- 

 tude of respiration, as a result of pituitary injection. Pantow 

 states that breathing stops for some time after the injection, 

 then begins again, then once more stops ; the primary stoppage 

 appears to be due to peripheral vagus stimulation. 



4. Effects on involuntary Muscles other than those of the 

 Vascular System 



(a) The Uterus. It was first recorded by Dale that in- 

 fundibular extract excites uterine contractions. The obser- 

 vation was confirmed by several investigators. The uterus 

 is extremely sensitive to the action of the extract, whether 

 in the body or treated as an isolated organ. Kehrer first 

 used the uterus in the latter way, and noted the action of 

 pituitary extract upon it. Engeland and Kutscher affirm 

 that they have succeeded in separating, by a method of 

 fractional precipitation, from an extract of the whole pituitary 

 body a basic fraction possessing the characteristic action on 

 the uterus, but not that on the blood-pressure. According to 

 Dale and Laidlaw, the isolated horn of the uterus of the non- 

 pregnant cat gives fairly good results, responding with but 



1 This is not always the case ; the precise conditions under which this, 

 occurs require careful investigation. 



