872 Dr. Barr/s Account of the Discoveries of Keber 



examination of all objects in the condition of minute divi- 

 sion, according to the above simple methods, teaches this. 

 Through this discovery, not difficult to test, the representation 

 of the composition of all organic structures out of the finest 

 fibres (the latter again representing a higher stage in develop- 

 ment of the nucleolus), given long since by Martin Bariy*, 

 receives its full confirmation and extension ; and it thence fol- 

 lows that the organic cell, which is regarded by many in the 

 present day as an " elemental structure,'' and in the cell-mem- 

 brane is said to possess a " structureless" covering, already 

 occupies a high step in the series of natural bodies. It is hoped 

 that evei-y one of those who may determine to examine it in a 

 minutely divided state, and without the addition of water, under 

 a superior microscope, will be obliged to admit that the cell- 

 membrane is far from being structureless. 



The addition of water, generally speaking, is a hindrance to 

 distinct perception of the microscopic pores, for sometimes the 

 textures — namely, in organic bodies — are thereby made to swell, 

 sometimes owing to altered refraction from passing through 

 pores filled with water, the rays of light no longer show with 

 the same distinctness the above-mentioned striking light-reddish 

 colour; yet, with long practice and great intimacy with the 

 subject, porosity, or at least traces of it, may be recognized even 

 though water has been added. 



c. Another method for finding microscopic pores in all dry 

 natural bodies, just as simple as that now mentioned, yet taking 

 up more time, is the following : — Carefully remove all dust, as 

 well from the body to be examined as from the glass on which 

 its particles are to lie. Then, upon one fixed spot of the glass, 

 make gentle but continued tappings with the body. By this 

 means there are usually loosed therefrom extremely delicate 

 spangles [Flitter chen], porous quite through their substance. 

 To prevent any confounding with dust-particles, it is needful with 

 the utmost care first to cleanse completely the receiving glass, 

 and even to employ the microscope in order to see that that 

 part of it upon which the objects to be examined are to fall is 

 completely cleansed. This method, it is true, takes more time 

 than that first mentioned, but it is very sure. It is also easy of 

 application, and this not only to dried animal membranes 

 (which for this purpose should be folded into a cone-like form), 

 and to all vegetable formations, but also to soft metals. Further, 

 on account of the great delicacy of the detritus hereby obtained, 

 it is most rewarding. For example, if one with forceps lays 

 hold of a little bit of gold-leaf and taps therewith gently upon 

 a fixed spot of the glass, there are loosened from the gold-leaf 

 * Phil. Trans., 1842. 



