698 



THE MICROSCOPE. 



possess important nervous functions ; and are now known 

 as " ganglionic cells." 



The muscular fibre, known as the non-striated, or invo- 

 luntary, consists of a series of tubes presenting a flattened 

 appearance, without the transverse striae so characteristic 

 of the former : elongated nuclei immediately appear upon 

 the application of a little dilute acetic acid. Professor 

 Wharton Jones first demonstrated this structure in his 

 lectures at Charing Cross Hospital, about 1843 : he was 

 led to infer, from appearances in very young fibre, that 

 the striped muscular fibre is originally composed of 

 similar elements to the unstrip&d, or plain muscular tissue, 

 which, in the process of deve- 

 lopment, becomes enclosed in a 

 sarcolemma (simple membrane) 

 common to many of them ; the 

 fibres then split into smaller 

 fibres (fibrillce). Thus account- 

 ing for the nuclei of striped 

 muscular fibre ; which, accord- 

 ing to his views, are " the per- 

 sistent nuclei of the primitive 

 muscular-fibre cells." 



The non-striated fibre is beau- 

 tifully seen in connexion with 

 the skin surrounding the hairs 

 of the head, a few fibres of 

 which are separately shown in 

 fig. 329. Professor Kolliker ori- 

 ginally described these muscles 

 of the skin, of which there appear 

 Fig. 329. A portion of the invoiun- to be one or two in connexion 



tary muscular fibre surrounding ,-, i_ t, r IT i 



the hair. with each hair-follicle, arising 



from the more superficial parts 



of the outer skin, then passing down to the root of the hair, 

 close behind the fat-gland, and there embracing it. It is 

 indeed most remarkable that skin, when covered with 

 hair, should alone be provided with these muscular 

 fibres ; the effect of the contraction of which must be 

 to thrust up the hair-follicles and depress the inter- 

 mediate portions of skin, and thus produce that peculiar 



