64 The Endocrine Organs 



A llow of saliva similar to that caused by excitation of the cervical 

 sympathetic is also produced, and is accompanied by contraction of the 

 vessels of the glands : the flow of saliva is little apparent in the dog, but 

 it is well marked in the cat, in which animal, as is well known, excitation 

 of the sympathetic in the neck provokes an abundant flow from the salivary 

 glands. The lacrimal glands are caused to secrete as well as the mucous 

 glands of the mouth, throat, and windpipe. These effects are accompanied 

 by pallor due to vasoconstriction, followed shortly afterwards by flushing. 

 There is increase of flow of gastric juice and bile, but not of pancreatic 

 juice. The sweat glands are said to be stimulated in the guinea-pig, but not 

 in the cat. The skin glands of the dog are caused to secrete. The 

 mammary secretion is unaffected. The flow of urine is increased by sub- 

 cutaneous but diminished by intravenous injection. The blood-flow is 

 increased in the suprarenals themselves. 



The autacoid has further been found to defer the onset of fatigue of 

 muscle and to assist its recovery. The arrectores pilorum, especially those 

 of certain parts, contract. Adrenalin also causes contraction of the pig- 

 ment cells both of the skin and retina of the frog. It is noteworthy that 

 sympathetic stimulation also produces this effect ; at least this is so for the 

 pigment cells of the skin. In birds some of the effects are different from 

 those obtained in mammals. Noel Paton and Watson found that in the 

 duck the effect of adrenalin is to cause decrease in the strength of the 

 ventricular beats, which may more than compensate for the arterial contrac- 

 tion simultaneously produced, so that a fall of blood-pressure may result. 

 There is also contraction of the intestine instead of inhibition. 



Although the rule is perhaps not entirely without exception, it may be 

 stated as a general principle that the result of suprarenal injection is 

 identical with that of stimulating the endings of the sympathetic nerves 

 throughout the body (Langley). 



As has already been pointed out, the above results are obtained even 

 if the sympathetic nerves have been divided and allowed to undergo de- 

 creneration. It has, therefore, been concluded that under the influence of 

 these nerves the tissues produce, either at the junction of nerve and muscle 

 {" myo-neural junction " of Elliott) or throughout the cell-protoplasm, a 

 material ("receptive or excitable substance" of Langley) w T hich reacts 

 with adrenalin, and not only with it but also with drugs, such as those 

 alkaloids which have a pronounced physiological action. And, further, 

 that this receptive substance increases either in amount or sensitivity after 

 the action of the nerves is withdrawn by their severance. 



Abolition of the effect of adrenalin in producing contraction of plain 

 muscle (and the same applies to the effects of sympathetic excitation) can, 

 as Dale has shown, be obtained by administering ergotoxine an amine 

 base obtained from ergot, and also obtainable from the products of breaking 

 down of histidine. Ergotoxine does not, however, paralyse the inhibition- 

 producing effect of adrenalin (nor the inhibition caused by sympathetic 



