This is the reason why, during emotion, we feel the urgent and repeated need to expel the urine, without the amount of accumulated liquid being such as to explain the necessity. We can no doubt all remember the annoyance which the contraction of this organ caused us on certain solemn occasions; for instance, when we had to make a speech, or present ourselves for an examination, or were anxiously expecting something. The feeling of contraction and pressure in the abdomen when we approach a precipice, or when we are in great apprehension, is solely due to the involuntary contraction of the bladder. We have shown that all causes producing a contraction of the blood-vessels have the same effect on the muscles of the bladder. I have often seen excitable, good-tempered dogs, in whom caresses and the sight of food were sufficient to produce such a contraction of the bladder, that the urine was expelled; and this suffices to confirm the fact that in our organism the same phenomena may be produced by opposite causes. In emotions violently agitating the nervous system, and especially in fear, the contraction of the bladder is so forcible that the will can no longer hinder the expulsion of the accumulated liquid; it is therefore not a paralysis, but too forcible a contraction of the walls of the bladder which causes the involuntary expulsion. * * * * * Let us throw a passing glance at what takes place in the _cloaca maxima_. The intestinal walls are as contractile as those of the bladder; nor need this surprise us, as they are furnished with smooth muscles, and receive nerves and blood-vessels from the same source. We know, indeed, that this canal is subject to rapid movements, for we have all frequently heard that rumbling noise of the intestines which we cannot suppress. If the abdominal walls were transparent, we should see, when this occurs, that there is a limited contraction of the intestinal walls which propagates itself slowly in the direction of the egress. These movements, called peristaltic, are present even when we hear no noise; they serve to mix the food in the stomach, promote digestion, and convey the useless residuum to the rectum. In paroxysms of fear the rapidity of these movements is so greatly increased that, in a very short time, they convey substances introduced into the stomach to the terminal portion of the intestines before there has been time to elaborate, digest, and condense them. It is therefore no paralysis which may, in certain circumstances, make the most courageous men appear ridiculous, it is a stream overflowing its banks--the intestines contracting so violently as to eject their contents rapidly from the organism.