The Mechanism of Spontaneous Secretion 99 



during sleep, 07 g during 9 hours, whereas during a meal 74-5 g 

 were produced in some minutes. Later investigators have likewise 

 tried to reduce or abolish the reflexly evoked activity by studying 

 the glands during sleep (Schneyer, Pigman, Hanahan and Gilmore, 

 1956). Under such conditions no flow was found from the parotid 

 gland. Sublingual and submaxillary secretion, investigated in one 

 subject only, was very slow, much smaller than that obtained in a 

 "resting" state. A reasonable way of eliminating the influence of 

 the central nervous system would be to give parasympatholytic or 

 ganglionic blocking agents. No such systematic investigations to 

 see whether there is a spontaneous secretion in man seem to have 

 been carried out. Nyman (1942), studying the efficiency of various 

 parasympatholytic drugs, observed apparently no parotid secretion 

 after the administration of such agents. Using a method in which a 

 compound for making dentures was allowed to set slowly in con- 

 tact with the palate, Ostlund (1953) could record a flow of saliva 

 from the palatine glands, seen as small pits in the material. A 

 continuous flow of saliva was obtained, partly at least no doubt 

 due to reflexes elicited mechanically. After administration of atro- 

 pine, no impressions were obtained in the material. The setting 

 of the compound took place, however, in a few minutes and a 

 small remaining secretion would probably not be revealed. The 

 observations by the same investigator on biopsy preparations of 

 palatine mucosa, quoted above, suggest the existence of some 

 spontaneous flow from the palatine glands. 



The function of spontaneously secreted saliva. A spontaneous flow 

 of saliva from some glands would provide a basal secretion to keep 

 the mucous membranes of the mouth and throat moist, for instance, 

 during sleep. With increased demands, for instance, during meals, 

 during speech or in some animals for thermoregulatory purposes, 

 reflex secretion can be superimposed upon the spontaneous flow. 

 In ruminants, the continuous secretion of strongly alkaline parotid 

 saliva apparently is of importance for the maintenance of the 

 optimal reaction of the gastric contents. 



The mechanism of spontaneous secretion. Experiments on tissue 

 cultures of gastric or intestinal mucosa suggest that secretion of 

 mucus may occur spontaneously (Florey, 1930, 193 1; Florey, 

 Wright and Jennings, 1941). Similarly, the mucous cells of the 

 sublingual gland and of the small salivary glands may be endowed 

 with the ability of secreting even in the absence of extraglandular 



