352 THE DUCTLESS GLANDS 



little diminished contraction to a second dose, after the first 

 has been carefully washed away. It is subject, however, to 

 inconvenient spontaneous slow variations of its average tonus, 

 and is apt to acquire a disconcerting rhythm. The uterine 

 horn of the young virgin guinea-pig is greatly superior in these 

 respects, its natural tendency, when left undisturbed in the 

 Ringer's solution, being to acquire a condition of complete 

 relaxation, broken only by a small rhythm. It is very sensitive 

 to the extract, which can therefore be given in very small 

 doses, and the tissue normally relaxes with promptitude to its 

 original level of minimal tonus on washing out and changing 

 the solution. This method is found to detect differences of 

 activity which escape recognition by the blood-pressure test, 

 and is employed by Dale and Laidlaw for standardizing pituitary 

 extracts. 



(6) The Bladder. The action of pituitary extract on the 

 bladder was first noted by Bell and Hick. In dogs and cats, 

 pituitrin stimulates to a considerable extent the musculature 

 of the bladder, and increases the excitability of the pelvic 

 nerve. 



(c) The Intestine. Bell observed the power of pituitary 

 extract to restore peristalsis to the paralytically distended 

 bowel, a capability which, according to Dale and Laidlaw, 

 is not represented by any definite action on the bowel of the 

 normal animal. But Beyer and Peter, working with the 

 surviving small intestine of rabbits, find that, after a preliminary 

 diminution in rhythm and tone, both these are very strikingly 

 increased. The rhythmical movements are often increased 

 tenfold. The first phase is considered by the authors to be 

 due to stimulation of the sympathetic fibres which inhibit 

 the muscle. The second phase, on the other hand, is due to 

 stimulation of Auerbach's plexus and the post-ganglionic 

 fibres. With very powerful doses, this second effect is very 

 slightly manifested or may be absent altogether, so that an 

 immediate and lasting inhibition may be the only result. 



It is usually supposed that the most distinctive difference 

 between the action of adrenin and that of pituitrin is that 

 the former relaxes the unstriped intestinal muscle, while the 

 latter uniformly contracts these fibres. But it has been shown 

 by Shamoff that certain posterior lobe preparations are capable 

 of producing relaxation of the isolated intestinal loop and of 



