70 ANATOMY AND PHYSIOLOGY 



sometimes they are largest at the base, or pear-shaped, 

 at other times regularly oval, or nearly globular. By far 

 the greater number of fibres exhibit no bulbs at their 

 terminations ; those which have them are always less in 

 diameter than the general average of the fibres. Some- 

 times, but not very frequently, the bulb exhibits faint 

 traces of a nucleus. On examining the dermal membrane 

 by transmitted light and a linear power of 666, I found 

 numerous globular cells collected in groups on various 

 parts of its inner surface, many of them having a well- 

 defined central nucleus ; and among these cells I found the 

 bulbs imbedded, with the fibres emanating from them, and 

 in no respect differing in appearance from the non-fibrous 

 cells around them (Fig. 259, a, a, Plate XII). On carefully 

 observing a number of these bulbous fibres that had been 

 removed from their positions on the membrane, I found 

 that the part of the fibre nearest to the bulb was frequently 

 flexuous, as if in a tender and immature condition, and in 

 these cases the marginal line of the fibre was continued 

 without the slightest break or interruption into and around 

 the bulb, as represented in Fig. 260, a, Plate XII. At this 

 period of the development the young fibre does not 

 measure above half the diameter of a mature one, and there 

 is no indication of an ultimate separation from the bulb ; 

 but when the fibre has attained nearly the full size the 

 separation is then distinctly indicated ; the basal end of 

 the fibre immersed in the bulb becomes hemispherical, and 

 a constriction appears at the junction of the fibre with the 

 exhausted cell. Sometimes, when thus affording indi- 

 cations of their ultimate separation, the cell still retains its 

 rotundity, but all indication of its nucleus has disappeared, 

 and it is perfectly transparent, as represented in Fig. 2 60 A 

 Plate XII, while in other cases it is visible only as a 

 collapsed and shrivelled vesicle adherent to the hemi- 

 spherical termination of the fibre, as represented in Fig. 

 260, c, Plate XII. I could not find the slightest indication 

 of bulbs amid the matted mass of fibres lying on the inner 

 surface of the membrane, and it was only at the torn 

 edges of the pieces of membrane under examination, or 



