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136 136 MUSCLE.

instance, when simply torn, separate into microscopic particles, which have an almost similar length. The same takes place, according to C. H. Schultz, during the digestion of muscle in the stomach, and, according to Purkinje, in muscle which is exposed to the action of an artificial digestive fluid. The observations of Valentin, already mentioned, admit, however, of no other explanation than that previously given; and the history of the period of formation deficient in my researches (from the cause before stated) may be completed from his. According to him, “globules of the primitive mass, arranged longitudinally, in a linear series, are present previous to the muscular fibres. The granules, then, seem to draw somewhat nearer together, and to coalesce, at some parts completely, at others, on the contrary, only on the one or other side. In this manner threads are formed, which present at some spots the appearance of strings of pearls, whilst at others they are less sharply indented; they are also often seen to be still wrinkled on one side, while on the other their margin is already nearly a straight line. The expression "granules of the primitive mass" (Urmasse), or other similar terms, have been hitherto used to denote either the elementary cells themselves or their nuclei, indiscriminately; in consequence of the distinction between them, and their relation to each other being unknown. In the passage quoted, Valentin cannot have meant the nuclei, for, as we have seen, they do not coalesce. What he calls globules of the primitive mass must, therefore, be the elementary cells furnished with their nuclei, and in their earliest stage of development; that is, before they have undergone any transformation. The following arguments may likewise be adduced in favour of the correctness of the explanation which assumes these “ globules of the primitive mass” to be cells. In the first place, the structure formed by their coalescence, namely, the primitive fasciculus of muscle, is hollow; and, secondly, in the early stage of development of the fasciculi, the cell-nuclei le just so closely together, as they would if each nucleus had pertained to a previously round cell. If these nuclei were subsequent formations, generated in the primitive fasciculus of muscle, as in a cell, they ought to be more numerous in old than in young muscles.

It, therefore, seems scarcely to admit of a doubt, that