MUSCLE. 137 



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 striie, 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 ab- 

 sorbed. 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. 1 



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 th?se 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, pa- 

 renchymal 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 arc after- 

 wards absorbed. 



The secondary muscle-cell passes subsequently through all 

 the changes incident to a simple cell. Its wall is at first thin, 



1 It might be important to examine whether the zigzag plications of muscles, 

 during contraction, have not perhaps some connexion with the length to which the 

 portion of a muscular fibre generated from one single cell has become expanded, so 

 that probably the angle of each flexion coincides with the point of junction of two 

 cells. 



