CONNECTIVE TISSUES. 351 



These methods inve a specific metachromatic stain of Mast- 



O I 



zellen on a liiHit oTouud. See also lor. dt two other methods 



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demonstrating plasma cells at tlie same time. 



705. Other Methods for Plasma Cells and. Mastzelleii. See, 

 inter itltus (in previous editions) PAPPENHEIM, Virchow's Arch., clxvi, 

 I'.'ol, p. 427; BERGONZINI, Anat. Anz., 1891, p. 506; SCHRIDDE, Anat. 

 Hefte, xxviii, 1905, p. 698; MAXIMOW, Arch. mik. Anat., Ixvii, 1906, 

 p. 686 ; ScHAFFEit, Cetitrabt. Phys., xxi, 1907, p. 261 (fixation in absolute 

 alcohol or 2 parts alcohol to 1 of formol, staining for half an hour in 

 methyleii blue, thionm or toluidin blue, in 70 per cent, alcohol with 

 1 per cent, of HC1) ; RANVIER, C. R. Acad. Sci., 1890, p. 165 (his 

 "Clasmatocytes": fix with osmium, stain with aqueous methyl violet 5B). 



'Fat. 



706. Fat and Lecithin. According to LOISEL (C. R. Soc. 

 .j lv, 1903, p. 703) lecithin is much less soluble than 

 neutral fats in turpentine or ether, and in general much 

 more stainable. To demonstrate lecithin, he advises as 

 follows : After fixation,, mordant the tissues with alum ; leave 

 them as little as possible in alcohol ; dehydrate with acetone, 

 ether, or benzin ; stain with hajmatoxylin, gentian, methyl 

 green, toluidin blue, Saurefuchsin or orange Gr, which stain 

 lecithin strongly, whilst leaving fat unstained. . 



DEFLANDEE (Journ. Anat. Phyx., 1904, p. 80) fixes in formol 

 of 4 per cent, and brings into acetone, in which fat is dissolved, 

 but not lecithin, which can then be stained by osmium. 



See also CIACCIO, Arcli. Zellforsch., v, 1910, p. 235; and 

 FISCHLER, Zeit. wiss. Mik., xxii, 1905, p. 262. 



707. Mounting Fat. Oamicated fat can generally be mounted 

 in balsam without special precaution. For delicate fats, 

 it may suffice to avoid absolute alcohol and essences as much 

 as possible, and mount direct in alcohol balsam or e-icpctral, 

 or clear with cedar oil, which has little solvent action. For 

 very delicate fats it may be necessary to avoid alcohol of 

 more than 70 per cent., or avoid it altogether, and mount in 

 glycerin or levulose. 



708. Removal of Fat. Fat can generally be dissolved out 

 by alcohol, ether, or chloroform and the like. Osmicated 



