CHANGES DURING SECRETION. 
487 
Three experiments were made ; the chorda tympani was stimulated on 
the left side. 
Amount of Saliva 
"I'l. lined. 
Weight of Active 
Gland. 
Weight of Resting 
Gland. 
Experiment 1 
2 

,, • ■ 
55 c.c. 
75 c.c. 
220 c.c. 
5 - 04 grins. 
5-42 ,, 
5-91 „ 
5 '06 grms. 
6-86 „ 
6-36 ,, 
In these experiments the left gland was the one that was caused to 
secrete, and there is some reason to think that the left gland is normally 
heavier than the right, for Bidder found this to be the case in eleven 
cases, and Heidenhain in two. 1 Pawlow, 2 however, noticed no appre- 
ciable difference in the amount of nitrogen contained by ten right 
and by ten left submaxillary glands of the dog. But so long as it is not 
shown that the right gland may lie normally heavier than the left, we 
may fairly conclude that there is a loss of weight by the gland during 
secretion and a gam of weight during rest. 
The question may be approached from another side. Microscopical 
examination shows decisively that during secretion the gland cells 
become smaller ; they must then, taken together, decrease in weight 
unless the percentage of solids in them increases. But, according to 
Heidenhain, the percentage does not increase during secretion ; on the 
contrary, it decreases. Thus, in one experiment upon a dog, in which 
about 220 c.c. of saliva were obtained by stimulating the chorda tympani, 
the percentage of solids in the resting gland was 28 - 3 per cent., and in 
the stimulated gland it was only 21*3 per cent,, so that there were 7 per 
cent, less solids on the stimulated side. 
This, it must lie remembered, applies to the gland as a whole. In con- 
cluding that there is a decrease in the percentage of solids in the actual gland 
cells, we assume that the percentage composition of the glands on the two sides 
i> approximately the same, that there is no appreciable difference in the amount 
of blood and lymph upon the two sides, and that the connective tissues in the 
gland are too small in amount or too constant in composition to affect the result ; 
these assumptions, however, appear to be justifiable. 
The other experiments made by Heidenhain '■' were as follows: — 
1. The left chorda tympani was stimulated and 75 c.c. of saliva obtained. 
The right submaxillary gland contained 23 per cent, of solids, the left gland 
18 - 6 per cent, — a decrease of 4*4 per cent. 
2. The left chorda tympani was stimulated and 55 c.c of saliva obtained. 
The right submaxillary gland contained 24 per cent, of solids, the left gland 
2T5 per cent. — a decrease of 3 5 per cent. 
Heidenhain found a slight decrease also in the percentage of solids on 
stimulating the cervical sympathetic. 4 The time of stimulation is given, but 
not the amount of saliva obtained. 
1 Op. cit., p. 57. 
2 Centralbl. f. Physiol., Leipzig 11. Wien, 1S8S, S. 137. 
z Stud. d. p/n/siol. Inst, zii Breslau, Leipzig, 1S6S, Heft i, S, 55. 
4 Op. cit., p. 66. 
