STRUCTURE OF THE THREAD. 125 



power of 300 diameters to see their structure much 

 more distinctly. 



At the larger end is situated a lozenge-shaped body 

 reaching to the middle ; from the inner end of this, 

 partly coiled round it, but extending through the 

 remainder of the capsule is the thread, lying in an 

 irregular, rather loose spiral, the appearance of which 

 differs considerably in different capsules. (See Plate 

 XXVIII. fig. 14). When it is projected, the wlwle 

 contents of the capsule disappear from the interior, 

 in a manner which induces me to believe, strange as 

 it seems, that the lozenge-shaped body at least, if not 

 the whole thread, is turned completely inside-out ; for 

 the extended thread is attached, not to the smaller, 

 hut to the larger end^ without the least appearance of 

 rupture. (Fig. 15). 



Now for the structure of the thread, or wire, for it 

 is as elastic as steel. This is marvellously elaborate, 

 especially when we consider its excessive tenuity, the 

 threads of the largest capsules being less than 7555th 

 of an inch in diameter, and those of the smallest per- 

 haps ^5-555th of an inch. The basal part of the thread, 

 to a length about half as-great-again as that of the 

 capsule, is clothed with alternate series of triangular 

 plates, laid one over the other, or imbricated, like the 

 scales of an artichoke. About half of this portion 

 is furnished with an armature of hairs rather closely 

 set, standing out at right angles, like a bottle-brush ; 

 they are twice or thrice as long as the diameter of the 

 thread, in the middle of the brush, but diminish to 

 each end; the individual hairs taper to a point. 

 (Fig. 16). 



