14 



SIMPLE FIBROUS TISSUES. 



endosmotic change of form in the corpuscles. But it is far simpler 

 to allow such films to dry, without any cover, and then merely to 

 cover them for protection ; and in this condition the general 

 characters of the corpuscles can be very well made-out, notwith- 

 standing that they have in some degree shrivelled by the desiccation 

 they have undergone. And this method is particularly serviceable, 

 as affording a fair means of comparison, when the assistance of the 

 Microscopist is sought in determining, for Medico -legal purposes, 

 the source of suspicious Blood-stains; the average dimensions of 

 the dried Blood-corpuscles of the several Domestic animals being 

 sufficiently different from each other and from those of Man, to 

 allow the nature of any specimen to be pronounced-upon with a 

 high degree of probability. 



558. Simple Fibrous Tissues. — A very beautiful example of a 

 tissue of this kind is furnished by the membrane of the common 

 Fowl's Egg ; 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 known 

 as the membrana putaminis. The latter may be separated by 

 careful tearing with needles and forceps, after prolonged maceration 

 in water, into several matted lamellae resembling that represented 

 in Fig. 374 ; and similar lamella; may be readily obtained from 



the Shell itself, by dissolving 

 away its Lime by dilute acid.* 

 — The Simply-Fibrous struc- 

 tures of the body generally, 

 however, belong to one of two 

 very definite kinds of tissue, 

 the 'White' and the 'Yellow,' 

 whose appearance, composition, 

 and properties are very dif- 

 ferent. 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 l-500th of an 

 inch, which are marked by 

 numerous 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 undu- 

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

 (Fig. 375). This tissue is easily distinguished from the other by the 



* For an account of the curious manner in which the Carbonate of 

 Lime is disposed in the Egg-shell, see § 599. 



Fig. 374. 



Fibrous membrane from Egg-shell. 



