The organic muscles do not appear to be subject to those irregularities of growth which the other muscles and the bones frequently exhibit. We know that the stature often remains stationary for many years, and that suddenly it acquires very great dimensions in a very short time; this phenomenon is remarkable especially after long diseases. Now notwithstanding these inequalities, the heart and all the other analogous muscles grow in an uniform manner; the regularity of the internal functions to which these muscles especially contribute, could not adapt itself to those aberrations which would be unable to disturb the functions of the locomotive organs. Besides, if they took place, the circulation, digestion, excretion of urine, &c. would exhibit corresponding aberrations; now this is never observed. The heart and the gastric muscles, &c. always grow in an infant whose stature remains stationary; they do not grow suddenly in one who grows at once; hence why the thorax and the abdomen become large in the first case, and remain contracted in the second in proportion to the extremities. Besides these two systems are never in precise relation of nutrition and power. I have already observed that very large organic muscles often exist with very small voluntary ones, and vice versa. Let us consider neither the growth nor nutrition in an uniform manner; each system is developed and increases in its own way; all are never found at the same periods of this function. Why? because nutrition, like all the other acts over which life presides, is essentially dependant on the vital forces, and these forces vary in each system. The growth of the involuntary muscular system is not uniform in all the organs which compose it. Each increases more or less, or is differently developed; one often predominates over the others in an evident manner; a bladder with strong, fleshy fibres, with columns as they are called, is often found in a subject with a debilitated stomach, with small intestines, &c.; reciprocally, the stomach, the heart, &c. have often an insulated predominance. III. _State of the Organic Muscular System after Growth._ It is from the twenty-fourth to the twenty-sixth year, that the organic muscles are completely developed. Then the thorax and the abdomen which contain them have their greatest capacity. These muscles are then as they are to remain through life; they have a density much greater than in youth; their power is increased and their colour is deeper. In general this is subject in the heart to frequent varieties, which coincide very nearly with the varieties of the preceding system. Acute and chronic diseases have nearly the same influence upon it. It is equally the index of the sanguineous, lymphatic temperaments, &c. by the different tinge it assumes. The colour of the gastric, intestinal and vesical fibres varies less; their whiteness, more uniform, is rarely influenced by diseases.