272 



THE MICROSCOPE AND ITS REVELATIONS. 



which (as may be seen by examining an egg whose shell remains soft for 

 want of consolidation by calcareous particles) consists of two principal 

 layers, one serving as the basis of the shell itself, and the other forming 

 that lining to it which is know as the membrana putaminis. The latter 

 may be separated by careful tearing with needles and forceps, after pro- 

 longed maceration in water, into several matted lamellae resembling that 

 represented in Fig. 459; and similar lamellae may be readily obtained 

 from the shell itself, by dissolving away its lime by dilute acid. 1 The 

 simply-fibrous structures of the body generally, however, belong to one 

 of two very definite kinds of tissue, the 'white 7 and the ' yellow, 'whose ap- 

 pearance, composition, and properties are very different. The white fibrous 

 tissue, though sometimes apparently composed of distinct fibres, more 

 commonly presents the aspect of bands, usually of a flattened form, and 

 attaining'the breadth of 1 -500th of an inch, which are marked by nume- 

 rous longitudinal streaks, but can seldom be torn-up into minute fibres 

 of determinate size. The fibres and bands are occasionally somewhat 

 wavy in their direction; and they have a peculiar tendency to fall into 



FIG. 459. 



FIG. 460. 



Fibrous membrane from Egg-shell. 



White Fibrous Tissue from Ligament. 



undulations, when it is attempted to tear them apart from each other 

 (Pig. 460). This tissue is easily distinguished from the other by the 

 effect of Acetic acid, which swells it up and renders it transparent, at 

 the same time bringing into view certain oval nuclear particles of 'ger- 

 minal matter,' which are known as ' connective-tissue corpuscles ' ( 651). 

 These are relatively much larger, and their connections more distinct, 

 in the earlier stages of the formation of this tissue (Fig. 461). It is per- 

 fectly inelastic; and we find it in such parts as tendons, ordinary ligaments, 

 fibrous capsules, etc., whose function it is to resist tension without yield- 

 ing to it. It constitutes, also, the organic basis or matrix of bone; for 

 although the substance which is left when a bone has been macerated 

 sufficiently long in dilute acid for all its Mineral components to be re- 

 moved, is commonly designated as cartilage, this is shown by careful 

 Microscopic analysis not to be a correct description of it; since it does 

 not show any of the characteristic structure of cartilage, but is capable 

 of being torn into lamellae, in which, if sufficiently thin, the ordinary 

 structure of a fibrous membrane can be distinguished. The yellow 



1 For an account of the curious form in which the Carbonate of Lime is dis- 

 posed in the Egg shell, see 710. 



