GENERAL CHARACTERS OF CONNECTIVE TISSUE CELLS. 59 



The network brought into view by the action of acetic acid 

 is darker, and the nucleus subsequently appears to be filled 

 with dark granules. 



In diluted solutions of potash and soda the nuclei of all 

 the cells in such specimens are distinctly defined. They appear 

 pale and vesicular. The cells acquire a border, seam or doubled 

 margin ; the granular portion of the cell diminishes in size with 

 the formation of larger or smaller clear drops, and, in conse- 

 quence of the coalescence of these drops, vacuolse become 

 developed, the formation of which was also observed by Kiihne 

 after the action of diluted acetic acid. 



As has been above stated, but few objects are well adapted 

 for the examination of connective tissue in the fresh state. 

 In the case of all thick, soft, and easily alterable masses, or in 

 those that are more dense and opaque, in order that the cells 

 may be exhibited, preparations must first be made by section, 

 or by teasing up the tissue with needles, and subsequently 

 agents employed by which they may be hardened and rendered 

 transparent. The objects that are capable of being examined 

 in a physiologically fresh condition may then be used as test 

 objects, and a comparison instituted between them. 



The best solutions are those of chromic acid, and especially 

 that recommended by Miiller,* consisting of two and a half 

 parts of chromate of potash, one part of sulphate of soda, and 

 100 parts of distilled water. If the latter be applied to the 

 test object, which has just been obtained in the perfectly fresh 

 condition, treated only with an indifferent fluid, and placed in 

 a moist cell, it may remain as long as may be desired in con- 

 tact with the reagent, and the changes produced by the harden- 

 ing solution may be examined from time to time. We may 

 then convince ourselves that Miiller's solution preserves the 

 cells in a nearly unaltered condition, so far as regards their 

 external appearance. They indeed become slightly shrivelled, 

 and the contour lines become smoother and more sharply 

 defined ; but the larger processes of the cells are completely 

 preserved. The granular character of the cell substance be- 



* See also Langhans, Wiirzburger Naturwissenschaftliche Zeitschrift, Bd. 

 v., p. 86. 



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