OF STEIATED MTJSCULAH FIBEE. 103 



is often observed to be situated near the border of the transverse diameter. In other 

 cases (Plate V. fig. 2) the nucleus appears nearer to one extremity ; sometimes it may be 

 considerably elongated (as if showing a tendency to commencing division (Plate V. figs, 

 3 & 4)), and occasionally opposite to it there may be a bulging in the outline of the cell. 



On the other hand, the elongation of the cells may be accompanied throughout by a 

 multiplication of the nuclei contained in their interior, giving rise to forms such as are 

 represented in Plate V. figs. 6, 7, 8, 9. By far the most ordinary condition which I 

 have seen, has been that the long diameter of the nucleus lies parallel to that of the 

 cell ; but in a certain number of cases, at least in those where two or more nuclei have 

 existed in its interior, they have been placed with their longer axis transverse to that of 

 the cell (see Plate V. figs. 8, 9). 



When the primary muscle-cell, whether with or without multiplication of its nuclei, 

 has thus become elongated to a certain extent*, a change in its structure becomes 

 apparent. Usually at one side a part appears lighter than the rest, and in this position 

 sometimes a longitudinal, sometimes a transverse striation makes its appearance, or occa- 

 sionally both longitudinal and transverse striation appear simultaneously. The contrast 

 between this portion (which when seen in profile is observed along the entire border of the 

 cell) and the dark pigmented condition of the remainder of the cell-contents is so great 

 as in some cases to lead almost to the supposition that it is a band of striated matter 

 laid in apposition with and external to the cell ; and this is especially the case in the 

 very earliest stages, when the altered part, as seen in profile, appears extremely narrow. 

 I measured it (Plate V. fig. 9) at a period when it was only ^ 5 „ q o inch in transverse 

 diameter. At a later stage (as in Plate V. figs. 5, 8, & 10) it will be seen that the 

 change is one really affecting the cell-contents ; there is no sharp line of demarcation 

 between the altered and unaltered portions, and over the former grains and granules of 

 pigment are seen scattered, but to a much less degree than is observed in the remainder 

 of the cell-contents. 



Gradually the pigment diminishes in the cells, and they may then be said to be sepa- 

 rable into two portions, one striated longitudinally and transversely, the other granular, 

 and more or less pigmented, and in this latter portion one or more nuclei are contained. 

 At this stage a distinct membrane may be seen bounding the granular portion, as in Plate 

 V. fig. 11. I believe that in the cases where the membrane can only be distinguished 

 on one side of the structure, its apparent absence on the other is only the result of the 

 position in which the object is seen ; for if the membrane (which is very thin and deli- 

 cate) lies in close apposition to the striated portion, its separate outline will be quite 

 undistinguishable ; and I am confirmed in this belief by the fact, that often in the same 

 preparation, and at stages not much further advanced, cells can be found on which a 

 membrane can also be seen on the other side of the striated portion (when seen in 



* I have, to avoid repetition, given the measurement of these figures in the special description of them at the 

 end of this paper, 



q2 



