Some Cases of Spontaneous Secretion 95 



simply as a synonym for continuous, permanent, basal or resting 

 secretion, as is often done. These terms say nothing about the 

 mechanism responsible for the secretory activity. Secretion des- 

 cribed by these words may be spontaneous; but it may also be 

 due to extraneous agents. 



Some cases of spontaneous secretion. The French physiologist 

 Colin seems to have been the first to report that in the ox the 

 parotid differs from the submaxillary gland in secreting continu- 

 ously, even between meals (see Milne Edwards, i860; Colin, 1871). 

 The work of Ludwig and Claude Bernard had at that time estab- 

 lished that salivary glands stop secreting immediately after dener- 

 vation. Eckhard (1867), finding that the parotid gland of the sheep 

 shows a continuous secretion like that of the ox, tried to denervate 

 the gland by cutting all nerves in the vicinity of the gland. Even- 

 tually the gland was attached to the animal via the blood vessels 

 only; nevertheless, saliva was discharged. He described the secre- 

 tion as continuous and spontaneous. An additional observation 

 was that the parotid gland of the sheep continues to secrete for 

 more than 15 minutes after death, although at a decreasing rate 

 (Brettel, 1869). The peculiar arrangement of the cranial innerva- 

 tion of the parotid gland in oxen and sheep was unknown in those 

 days. Moussu (1888) discovered that the buccal nerve carries 

 secretory fibres for the gland along the salivary duct ; it was shown 

 that there is some flow of saliva even after section of this nerve 

 (Moussu, 1890; Eckhard, 1893). This type of secretion seems to be 

 characteristic of the parotid gland of ruminants ; the gland of the 

 horse, for instance, rests between meals (Colin, 1871; Ellenberger 

 and Hofmeister, 1887). 



The sublingual gland of the cat offers another example of con- 

 tinuous salivary secretion (Emmelin, 1953). In the cat under chlo- 

 ralose anaesthesia there is no parotid or submaxillary secretion, 

 whereas the sublingual gland incessantly discharges small amounts 

 of saliva at a fairly regular rate. The flow is seen in decerebrate or 

 spinal preparations as well. Section of the parasympathetic and 

 sympathetic fibres of the gland does not affect the secretion al- 

 though stimulation of these nerves accelerates the flow (see Fig. 

 3.5). The secretion goes on after injection of a dose of atropine 

 which abolishes the secretory effect of chorda stimulation, or a 

 dose of dihydroergotamine which annuls the effect of sympathetic 

 stimulation. The flow continues at an unchanged rate in a gland 



