112 
MESSRS. J. R. LANGLEY AND H. M. FLETCHER 
for some little distance, the chordo-lingual cut, and the chorda tympani isolated for a variable distance. 
Dm-ing stimulation the lingual nerve was raised by the ligature, and the electrodes slipped under the 
chorda; in the intervals of stimulation the chorda was covered up. 
The interrupted current of a du Bois’ induction machine was used for stimulation ; in the account of 
the experiments, the distance of the index of the secondary coil from the primary is given in centimetres; 
thus, c = 12'5 indicates that the index of the secondary coil was at 12'5 cm. of the scale attached to 
the machine. One Daniell’s cell was used, but not the same in the several experiments. 
A glass cannula was tied in Wharton’s duct, and, for convenience of collecting the saliva and of 
counting the drops, the cannula was bent at the end. The object of counting the drops was to note 
variations in the rate of secretion whilst collecting any one sample of saliva; since the size of the drops 
depends upon the rate of secretion and upon various other conditions, the number of drops collected in 
successive samples often gives a very rough indication only of the amount of saliva in each. 
The saliva was collected in small-necked bottles graduated in centimetres, so that the amount of saliva 
obtained at any time could be roughly estimated. The saliva was measured in the following way :—The 
level of the saliva in the bottle was marked by a strip of adhesive paper, the bottle was emptied and 
dried, and then water was allowed to run into it from a burette up to the level of the strip of paper. 
Before collecting a sample of saliva under any given conditions, 1 to .3 c.c. of saliva obtained under 
these conditions were thrown aiuay. —In the account of the several experiments the amount thrown away 
is, for special reasons, occasionally mentioned, and always when the amount thrown away was less than 
•75 c.c. It may be mentioned that one to two drops is probably as much as the gland ducts and lumina 
contain. 
The sympathetic nerve, when it was necessary to stimulate it, was dissected out from the vagus in the 
neck, ligatured, and cut. When salt solution or other fluid in quantity was injected into the blcod it was 
first warmed to about 38° C. 
Pilocarpin was injected into the blood as jsilocarpin nitrate, and atropin as atropin sulphate. 
Method of Analysis .—The amount of each sample of saliva collected is given in the 
description of the experiments. When there was sufficient saliva, 2'8 to 3‘0 c.c. 
were taken for analysis. The weighed quantity of saliva was dried in a platinum 
crucible at 100° C. This temperature was found to be quite high enough to 
drive off all the water in five to six hours. When further heating of the crucible 
produced no diminution in weight, the weight of the residue, after cooling over 
sulphuric acid, gave the total amount of solids. The residue was then carefully 
ignited over a Bunsen flame, the crucible being held in the flame by means of tongs. 
The smallest possible amount of heat necessary to secure complete ignition of the 
organic compounds was einployed, in order to prevent loss by volatilisation and 
possible loss by some of the fused salts creeping over the edge of the crucible. Less 
than three-cpiarters of a minute generally sufficed to burn off all carbonaceous matter. 
The residue, weighed after cooling over sulphuric acid, gave the total salts. The 
weighing was performed to '0001 grin. In the Tables we have given the percentage 
composition of the various samples of saliva to three places of decimals only, since, for 
our purposes, the inaccuracy incidental to the determination of the rate of secretion 
made of no value the fourth—and sometimes the third—place of decimals in the 
percentage composition. 
