5 oS THE SALIVARY GLANDS. 
Experiment 1. — The Parotid Gland of the Dog. 1 
Saliva obtained by Stimulating — 
Duration of 
Stimuli. 
Amount of Saliva Pel "? enta ? e of Percentage of 
<*> Uected - SulSel «* 
Jacobson's nerve 
Jacobson's nerve and the 
sympathetic 
IS mill. 
30 min. 
1 
3-11 grms. 0-7G 0-26 
3-63 grms. 1'41 0-32 
1 
Experiment 2. — The Parotid Gland of the Rabbit.' 2 
In this experiment pilocarpine was injected, and a sample of the saliva 
collected. The cervical sympathetic was then stimulated ; during the stimula- 
tion the secretion became slower until it stopped ; on its cessation the stimula- 
tion was also stopped. After a short time the flow began again ; when about 
three drops had been secreted the sympathetic was again stimulated, and so 
on, till a second sample of saliva was collected. 
Saliva obtained from 
Rate of Secre- 
tion per Minute. 
Percentage of 
Organic 
Substance. 
Percentage of 
Salts. 
Pilocarpine . 
Pilocarpine and sympa- 
thetic stimulation 
0-22 c.c. 
0-062 c.c. 
0-39 
3-62 
0-85 
075 
Effect of Variations in the Amount and Quality of the Blood 
supplied to a Gland, upon the Amount and Percentage 
Composition of the Saliva Secreted. 
In order to form a satisfactory theory of the action of secretory 
nerves, it is of the greatest importance to know how far variations in 
the amount and character of the blood flowing through the gland affect 
the amount and character of the saliva. Our information on this point 
is unfortunately still vague in many respects. 
Certain broad facts can be readily observed by compressing the 
carotid artery on one side, after tying the carotid artery on the other 
side, and the subclavian arteries on both. The gland-veins are cut, so 
t hat the amount of blood flowing through the gland can be roughly 
determined; and the chorda tympani is stimulated during different 
degrees of compression of the carotid. 
When the carotid is compressed to a moderate extent, the chorda on 
stimulation will not cause so much increase in the blood flow through 
the gland as it otherwise would, but it will nevertheless cause a con- 
siderable increase, and the blood will issue from the vein of an arterial 
colour. In such case, according to Heidenhain, 3 the amount of saliva 
obtained by a given stimulus will be of normal amount. 
1 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1S7S. Bd. xvii. S. 31. 
2 Heidenhain, op. cit., S. 40. 
3 Heidenhain (Stud. d. physiol. Inst, zu Brcslau. Leipzig, S. 98) appears to refer to an 
increase of blood flow above that occurring with partially compressed carotid, and not to an 
increase above the normal blood flow. 
