Some anatomists reckon more than this number, others less, for the reason that, at different periods of life, the number of pieces of which one bone is formed, varies. Example. The breast-bone, in infancy, has eight pieces; in youth, three; in old age, but one.
Compare 1, 1, Fig. 28, with 2, 2, 2, Fig. 48.
In the plates illustrating the muscular system, the names of such muscles are given as are referred to in the paragraph “Practical Explanation.” These names need not be committed to memory. If a pupil wishes to acquire a knowledge of the general attachment of the muscles represented in the plates, he can do so by comparing the muscular plate with that of the skeleton, (fig. 28.)
It appears to be a fact, that no two important organs can be called into intense action at the same time, without injury to both, as well as to the general system. This arises from the circumstance that an organ, when in functional action, attracts fluids (sanguineous and nervous) from other organs of the system. Except in a few instances of high health in youth, the power of the system is not adequate to supply more than one organ in action with the appropriate fluids at the same time.
See [Chapter XII].