[31] The contractility in the different organs in which we can observe it does not exhibit characters so striking as those which Bichat here assigns to it, and the motions which he ranks in the same class have the greatest differences among them. To be convinced how little justice there is in this division, it will be sufficient to trace the progress of the food, along its whole course, to the interior of the digestive canal. The first act which is presented to our observation is entirely voluntary; this is mastication; the act which follows it is not so completely so. Deglutition in fact can sometimes take place against the will, if a body of a proper consistence is at the entrance of the pharynx. We have but an imperfect control over the muscles of the uvula and the velum palati, if we wish to move these parts separately; we have perhaps less power still over the contraction of the muscles of the pharynx, though they do not appear to differ from the locomotive muscles, either in their symmetry, or in the arrangement and colour of their fibres, or in the nerves which they receive; nor finally do they differ in the sudden, instantaneous contraction, wholly different from the slow contraction, the vermicular motion of the stomach and intestines. After having passed the pharynx, the alimentary mass enters the œsophagus. The motions are there still under the influence of the nerves; but they are not at all under the influence of the will. The muscular layer which produces them has not the appearance, the red colour of the voluntary muscles; but it still preserves something of the sudden motion of their contraction. Hence we see, that the motions of the œsophagus cannot be ranked either among the motions of organic life, since they cease by the division of the nerves, or among those of animal life, as they are not under the influence of the will. It is remarkable also that Bichat, who, in this and the following paragraph, announces the characters of the different kinds of contractility, does not speak of the œsophagus, whilst he offers as an example the motions of the bladder, the heart, the stomach and the intestines.