THE PARALYTIC SECRETION. 521 
The peripheral nerve-cells 1 in connection with the gland may be 
spoken of as a local nerve-centre. This local centre is capable of 
exciting the gland-cells to activity long after the chorda tympani, which 
normally conveys impulses to it from the central nerve-centre, has 
degenerated. 
Heidenhain suggested that the paralytic secretion might be due to a 
stimulation of the gland-cells by the decomposition products of the 
stagnating saliva. He observed that if the duct were clamped for about 
a day, a slow secretion of watery saliva ensued. The cases, however, are 
hardly comparable, inasmuch as, whilst the duct is closed, secretion is 
formed which partly distends the alveoli and partly is forced out of the 
ducts and lumina. and bathes all the tissues of the gland. 
A final explanation can hardly yet be given, but some observations 
made on the cat lead me to think that the secretion is the result of 
nervous stimuli. In the cat the paralytic secretion is much diminished 
and even stopped by excess of chloroform and by apncea; and is 
increased markedly by dyspnoea : the dyspneeic flow takes place more 
readily than on the opposite side, and, so far as can be judged, more 
readily than in a normal gland. These results indicate that the 
paralytic secretion is due chiefly, at any rate, to a slight continuous 
excitation of the local nerve mechanism. 
Heidenhain found that the paralytic secretion also occurred in the dog, 
when the superior cervical ganglion was excised at the time of section of 
the chorda. In this case the secretion is due wholly to local changes. 
In the early stage of secretion in the cat, three days after section of the 
chorda alone, I noticed that section of the cervical sympathetic very 
much diminished or even stopped both the paralytic secretion and the 
dyspneeic secretion, although, in the later stages, section of the cervical 
sympathetic had little or no effect. Probably, then, if the sympathetic 
is intact, the secretion which occurs in the first few days alter section of 
the chorda is largely due to impulses travelling down the sympathetic 
from the central nervous system. 
The loss of weight which occurs in the submaxillary and the sub- 
lingual glands, after section of the chorda tympani, amounts in a few 
weeks to one-third to one-half of the original weight of the glands. 
Bradford has shown that section of Jacobson's nerve causes a similar 
loss of weight in the parotid gland 2 of the cat. Whether complete 
atrophy takes place, and if so what time it requires, there is no evidence 
to show. 
In the submaxillary gland, and no doubt in the others also, the loss 
of weight is due to a loss of cell substance by the individual cells. And 
this loss is simply an instance of the gradual atrophy which occurs in 
tissues in the absence of functional activity. The persistent slight 
activity, of which the paralytic secretion is the sign, is quite insufficient 
to replace the normal exercise of function. 
In the dog, according to Heidenhain, the paralytic gland contains a 
number of alveoli, presenting the appearance of the alveoli of an active 
gland. In my experiments, both on the dog and cat, the gland-cells were 
undoubtedly in the resting state. In the cat the saliva obtained by 
1 Six weeks after section of the chorda in the cat, when the submaxillary gland had lost 
one-third to one-half of its weight, the nerve-cells in the alcohol-hardened gland presented 
no certain difference from the nerve-cells of the gland of the opposite side. 
- Bradford did not observe a paralytic secretion from the parotid. 
