6

PROGRESS OF ORGANISATION

adapted to that rapidity of supply and digestion which is requisite to build up quickly the various textures. The organs of deglutition are perfect. The stomach, the intestines, the liver, spleen, pancreas, and the lacteal system of vessels, are fully developed and completely perform their duties, and thus the nutritions matters are duly collected and conveyed to the heart. All parts of that organ are complete; its functions are performed with a rapidity and vigour greater than in adult life, but which the wants of the infant system require. The pulsations vary from 120 to 130 in the minute;1 the capillary vessels are numerous and distensible; the coats of the veins firm, and their valves strong. Thus the formative fluid is rapidly carried to all parts, and the returning blood firmly sustained

Dr. Carpenter gives the following table of the frequency of the pulse at different periods:

* It has been fully demonstrated by Sir Clifton Wittringham, that the coats of the veins in young animals far exceed those of the arteries in density, and that consequently they are less subject to distension.

in its passage back to the heart. The lungs, the diaphragm, the parietes of the chest, are all complete in their development and action; the respiration is much more rapid than in after-life, being in relative proportion to the greater frequency of the heart's action. Less change is effected in the blood than in mature life, less carbonic acid is given off, and less oxygen received; for as the system has to be built up, not changed in its structure, the lacteal vessels are very active, whilst those absorbent vessels which have to remove effete portions from the whole body have but little duty to perform. It follows from this that but little caloric is given off, and that there is a deficiency of animal heat. Thus organic life is vigorous and active from the first, for much is to be done; the infant frame is very imperfectly developed, and incapable of performing any of the animal functions. The various organs of animal life must be gradually completed and consolidated. Increase of size and perfection of organization are required, and the organs of nutrition therefore are actively employed in receiving supplies and converting them into organized animal matter.

The Organs of Animal Life.-These have been well termed " organs of relation," because they connect

in texture, incapable of much exertion, and attached to the cartilages or bones by tendinous extremities, which are soft and weak. We, scarcely seem to contemplate the rudiments of those organs, which in future time may perform such marvellous feats of strength and agility.

The Voice.-The shrill cry of infancy differs not more from the full tones of manhood, than do the organs of voice in infancy from those of adult age. These parts are composed chiefly of muscles and cartilages, none of which are fully developed in early life; but as they gradually become so, the voice becomes changed, until at the period of puberty a large and sudden development occurs, and consequently at that period the voice, especially of the male, is greatly altered.

The Brain and Nervous System.—The brain in infancy is very soft, almost pultaceous, and large in proportion to the body, indeed it does not appear to get larger after the third year of life, but increases in density and weight up to the close of the seventh. The spinal marrow resembles the brain in condition in infancy, but is somewhat more dense and complete, as the difference of its duties would indicate, being chiefly the organ of sensation and locomotion, while the brain is chiefly the organ of the mind.

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