56 MUSCLES. 



transverse section, it is found that the changes just 

 described take place from its circumference towards 

 its centre, very rarely in the opposite direction. Fi- 

 nally, the fibrillse increase in number, whilst their 

 newly formed nuclei are absorbed, and the mus- 

 cular fibre gradually puts on its permanent appear- 

 ance. 



The following is a summary, in two words, of this 

 process which seems best borne out by facts : fusion 

 of embryonic cells, T\ hich by their union form a tube, 

 or myolemma; metamorphosis of its contents into 

 elementary granules, and their subsequent develop- 

 ment into fibrillse or discs. 



During the earlier periods of development and 

 growth of the fibres of muscle, they are enveloped by 

 a large number of elementary cells some oval in 

 shape, others smaller and round. Of these, the 

 greater proportion are destined to form the connect- 

 ing tissue and other parts which constitute a com- 

 plete muscle ; and the rest, after having contributed, 

 no doubt, to the growth of the persistent elements of 

 the tissue, fade and disappear. The muscular fibres 

 of the heart are developed in accordance with the 

 same rules, with this exception, that, in place of the 

 fusion and subsequent transformation of simple cells, 

 these phenomena are accomplished by means of 

 branching, or star-shaped cells ; hence arises the 

 branching character of the fibres of this organ. The 

 fibres of muscle, having attained their complete 

 development, remain permanently, for an indefinite 

 period, in this state, and the metamorphoses which 

 occasionally occur in their interior, are marked 



