number, to place this matter in a plainer light before our readers. In the mean time we may remark, that GLISSON seems to be the first of those who have placed the subject fairly before the medical public; for although faint traces of a similar theory may be perceived before him, especially by translating terms into their equivalents, yet he has the merit of using a term which, in spite of all subsequent modifications, is in daily use. GLISSON'S latitudinarianism may be contrasted with HALLER'S rigid application: for the latter says, "I call that an irritable part of the human body, which on being touched by a foreign body, renders itself shorter;" thus while GLISSON attributes his triunit of perception, appetence, and motion to all the tissues and fluids, HALLER confines it to muscular fibre alone. No one can doubt that the membranes of the body are endowed with vital properties, but yet they do not shorten themselves on being touched by a foreign body. BICHAT has distinguished their vitality as organic vitality, and the contractile qualities displayed are divided into insensible organic contractility, and into contractility of tissue: but these sorts of contractility mount up by insensible gradations. He says, that "entre la contractilite obscure mais reelle, necessaire a la nutrition des ongles, des poils, &c. et celle que nous presentent les mouvements des intestins, de l'estomac, &c. il est des nuances infinies, qui servent de transition: tels sont les mouvements du dartos, des arteres, de certaines parties de l'organ cutane," &c. We will close with a comparison between GLISSON'S irritability, and BICHAT'S contractility. At page 70 of the Treatise _sur la Vie & la Mort_, BICHAT supposes that a "muscle enters into action, 1st. by the influence of the nerves which it receives from the brain, and this is a case of contractile animale," (which differs in no respect from perception regulated by animal appetency of GLISSON). 2ndly. According to BICHAT, the muscle enters into action "by the excitation of a chemical or physical stimulant applied to it, and which artificially determines a movement of the whole muscle, analogous to what is natural to the heart, and other involuntary muscles. This is sensible organic contractility or irritability," and corresponds to the sensitive perception of the old English physiologist. In the 3d place it enters into action by the stimulus of the fluids which circulate in it, and this is insensible organic contractility or tonicity of BICHAT, and is nothing different from GLISSON'S natural perception. BICHAT makes a fourth case; as for example, when a muscle is divided across, it contracts by a _contractilite de tissue_, or _par defaut d'extension_. We do not perceive how GLISSON'S natural perception can be applied to this case, but he treats of it in his fifth chapter under the head of Cessatio: it is that state to which a fibre is reduced when left to itself, and freed from all stimulus.