224 CLARKE, ON STRIPED MUSCULAR FIBRE. 



of oue overlying and coalescing with those of another. Occa- 

 sionally I have seen a number of nuclei arranged in a single 

 linear series_, and in contact, but slightly overlapping each 

 other, and held together by a common layer of condensed 

 blastema, formed by the coalescence of their processes (fig. 5 c) . 

 Such an arrangement is only a repetition of that which takes 

 place at a and b in the same fig. In some cases it may be 

 seen that granular processes have grown from opposite sides 

 of the nuclei, and thus formed with them bodies which have 

 the shape of fusiform, nucleated cells, but do not appear to be 

 enclosed by a distinct wall. A number of these bodies may 

 become applied to each other at their sides, but in such a way 

 that one is in advance of the other. Fig. 5 d is an exact 

 representation of a fibre so formed, from the anterior extremity 

 of a chick, between the fifth and sixth days of incubation, and 

 magnified 670 diameters."^ After a time the separate bodies 

 coalesce, and, apparently, by a longitudinal growth, the fibre 

 straightens and assumes the appearance of a band, while the 

 distances between the nuclei become increased. At fig. 6 b 

 four such fibres are represented. In the muscles of the trunk, 

 however, the nucleated fusiform bodies from which these 

 fibres are formed are seldom so well defined and arranged 

 with so much uniformity as in the case just described. More 

 frequently a series of nuclei, at variable distances from each 

 other, are partially or wholly surrounded and united by an 

 irregular condensation of blastema, as represented at fig. 4 b. 

 At the same time the column thus produced is isolated on 

 one side by a further layer of material, in the form of a distinct 

 border, which is probably effected under the influence of the 

 nuclei (fig. 4 b). A similar border is subsequently formed 

 along the opposite side, until the fibre is completely isolated 

 from the surrounding substance. 



In some instances, but less frequently, nucleated bodies, 

 ha^■ing the shape of fusiform cells, taper at their extremities 

 into long, slender fibres, by which they become united in 

 linear series (fig. 6 a) . These appear to belong to tendinous 

 tissues. 



Besides the muscular fibres above described there are other 

 fibres of a different nature found in the same field, and which 

 belong apparently to the muscular sheath, as they are mostly 

 seen along the borders of dissected portions of muscles. Their 

 nuclei are small, but of uniform size, and are oval, fusiform, 

 and pyriform. In the formation of these fibres (fig. 4/) the oval 



* The edges of the bodies, however, at their hnes of junctiou, have been 

 intentionally made a little sharper and more distinct than they were seen to 

 be in the preparation. 



