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Rh each primitive muscular fasciculus is a secondary cell, formed by the coalescence of primary round cells, each furnished with a nucleus, and which were arranged together in a row. After the coalescence of the contiguous portions of the cell-walls has taken place, an absorption of the septa remaining between the cavities of the two neighbouring primary cells must commence, since no such septa can be perceived within the secondary cell at a later period. If the little transverse striæ, by which the cavity of the fibres is sometimes divided, be actually nuclei placed transversely upon their edges, they are probably such as lay upon that part of the wall of the cells which was absorbed. It seems that the coalescence of the cells, however, is not sufficiently complete to prevent a separation taking place more readily at the points of junction than elsewhere, and on this the phenomena of the artificial division of muscle before mentioned probably depend.

When I made my first communication upon the formation of the primitive fasciculi of muscles by the coalescence of cells (Froriep’s Notizen, No. 103), the only corresponding instances known to exist among vegetable cells were those of the spiral and lactiferous vessels. The interest attached to the subject has very much increased since Meyen’s discovery of a much more striking analogy in the cells of the liber or inner bark—(bastzellen). (Wiegmann’s Archiv, 1838, p. 297.) He found that these long-extended cells, when boiled in hydrochloric acid, fell into small particles of nearly equal length; and investigation into the development of the cells of the liber in buds showed, that in the early period a corresponding quantity of distinct, somewhat longitudinally extended, prismatic, parenchymal cells are present, which are placed with their extremities accurately arranged one upon another, that they unite together at those parts, and that their septa are after-wards absorbed.

The secondary muscle-cell passes subsequently through all the changes incident to a simple cell. Its wall is at first thin,