ON THE NATURE OF INTESTINAL SECRETION, 55 
There is, however, yet a third way in which secretion may be induced, and 
that a somewhat extraordinary one, viz. by paralysis of certain nerves going 
to the gland instead of by irritation. What the cause of this secretion is 
has not been clearly made out, but the secretion itself is distinguished by its 
profusion and long continuance. It has not yet been ascertained whether 
this kind of secretion is arrested by atropia or not, We propose to ascertain 
this in future experiments ; but as the question did not lie directly within 
the limits of our present investigation (although closely connected with it), 
we have not as yet attempted to solve it. There are, then, three ways in 
which secretion may be induced in the salivary glands :—Ist, by direct irri- 
tation of the secreting nerves ; 2nd, by reflex irritation of these neryes; and 
ord, by paralysis of nerves, 
We have entered thus fully on the physiology of secretion in the submaxil- 
lary gland, because in it alone has the secreting process and the action of 
nerves upon it been at all fully studied. 
Regarding secretion in the intestines very little is known, but it is probable 
that the process is performed in much the same way as in the salivary 
glands. 
The reasons for this belief are as follows :— 
1st. When the process of digestion is going on and the food is present in 
the intestines, their vessels are fuller than at other times, just as they are in 
the salivary glands, 
2nd. Stimulation of the mucous surface of the intestire induces secretion of 
intestinal juice, just as stimulation of the mucous membrane of the mouth 
induces a flow of saliva. 
3rd, Section of all the nerves going to the intestine produces a profuse 
secretion of intestinal juice, which at once reminds us of the paralytic secre- 
tion observed in the submaxillary gland after section of its nerves, 
This secretion of the intestine was first discovered by Moreau, who isolated 
a loop of intestine by means of ligatures, and then divided all the nerves 
passing to it on their course along the mesentery. On examining the intes- 
tine after four hours, the loop which had previously been empty was dis- 
’ covered to be filled with fluid. 
This fluid was investigated chemically by Professor Kiihne, now of Heidel- 
berg, who found it to be neither more nor less than very dilute intestinal juice 
and almost identical in composition with the rice-water fluid which is poured 
from the intestines so abundantly in cholera (Kiihne and Parkes), 
The intestinal secretion can therefore be excited like the salivary one:— 
1st, reflexly by stimulation of the mucous membrane of the intestine ; and 
2nd, by division and consequent paralysis of all the nerves passing to the 
intestines. 
Unlike the salivary secretion, however, it has not yet been induced by 
direct stimulation of the secreting nerves; and, indeed, these nerves are not yet 
known. It is not improbable, however, that they are extremely short, and 
are situated in the wall: of the intestine itself, in which, indeed, the whole 
apparatus necessary to secretion would appear to be contained. This consists 
of the secreting glands, vessels, and nerves. The nerves immediately inducing 
secretion are probably the ganglia contained in Meissner’s plexus, the 
short afferent fibres’ passing to these from the intestinal mucous membrane, 
and the short secreting fibres passing from them to the intestinal glands. 
The stimuli which excite secretion, when applied to the intestinal mucous 
membrane, are of various sorts. 
Mechanical stimulation, such as tickling the surface of the mucous mem~ 
