54 Innervation of the Glandular Elements 



priscol, on the other hand, the constriction is lost but the secretion 

 preserved (Emmelin, 19556). Of course, these observations cannot 

 be used as arguments to show the presence of special secretory 

 fibres. It does not seem likely that it would be possible to stimulate 

 secretory fibres electively near the exit from the spinal cord. 

 Langley (1892), stimulating different spinal nerves, concluded that 

 "the origin of the secretory fibres in the Cat and Dog bears, then, 

 a very close resemblance to the origin of the vaso-motor fibres in 

 these animals". Some light may be thrown on the problem under 

 discussion by experiments on the degenerating sympathetic fibres. 

 In the cat, it is true, the secretory and vascular effects seem to dis- 

 appear at about the same time after section of the sympathetic 

 trunk (Jurist and Rabinovich, 1924); but in dogs Sinelnikoff(i92i) 

 was able to obtain a secretory effect unaccompanied by vasocon- 

 striction between the third and the sixth day after the nerve had 

 been cut. The secretory effect was apparently mostly demonstrated 

 as an "augmented secretion" after chorda stimulation. Similar ex- 

 periments led Stavraky (1931) to the conclusion that such an 

 "augmented secretion", obtained about 90 hours after the opera- 

 tion, is not a "true augmented secretion" but a mechanical phe- 

 nomenon, due to stimulation of surviving motor fibres. In some 

 experiments, however, Sinelnikoff obtained a flow of saliva on 

 rhythmical stimulation of the degenerating nerve even without 

 previous chorda stimulation, and not accompanied by vasocon- 

 striction. It might be that this effect was due to stimulation of real 

 secretory fibres. 



An indication of an influence, exerted under physiological con- 

 ditions by the sympathetic fibres on the secretory cells may be that 

 removal of the superior cervical ganglion is followed by the develop- 

 ment of a supersensitivity of the gland cells to chemical agents 

 (Simeone and Maes, 1939; Emmelin and Muren, 1951). This does 

 not prove, however, that there are separate secretory fibres, but it 

 shows that the sympathetic fibres normally have some kind of 

 action on the secretory cells, even if it may be exercised by sym- 

 pathin diffusing from the vasomotor nerve endings. Actions on 

 the gland cells, observed in an experiment during stimulation of 

 the sympathetic fibres, are not merely due to abnormal conditions, 

 for instance the use of unphvsiologically high frequency of 

 stimulation. 



Claude Bernard (1858) found that a permanent flow of impulses 



