356 CONNECTIVE TISSUES. 



over a layer of powdered alum a couple of fingers deep) ; xylol, 

 balsam. 



(6) As No. 3, su.pm, after a foregoing stain of two minutes in 

 polychrome methylen blue. 



See also EHRLICH in Virchow's Arch., clxxv, 1904, p. 198. 



765. EHRLICH'S Original Method for Mastzellen (Arch. mik. Anat., 

 xii, 1876, p. 263). Stain for at least twelve hours in- 

 Absolute alcohol . . . . . 50 c.c. 

 Water 100 



Acid. acet. glacial . . . . . 12 J 

 -to which has been added enough dahlia to give an almost satu- 

 rated solution. Wash out with alcohol, and mount in resinified 

 turpentine. 



See also SCHIEFFERDECKER and KOSSEL'S Gewebelelire, p. 329. 



766. Mastzellen, UNNA'S Latest Methods (Encycl. mik. Techn., 

 1910, ii, p. 72). (1) Stain three hours to overnight in polychrome 

 methylen blue with a knife-pointful of alum to a watch-glass of the 

 stain, rinse ; alcohol, oil, balsam. (2) Stain in polychrome methylen 

 blue quarter of an hour, rinse, then ten minutes in glycerin- ether, 

 702, wash thoroughly, alcohol, oil, balsam. 



These methods give a specific metachromatic stain of Mastzellen 

 on a light ground. See also loc. cit., two other methods demon- 

 strating plasma cells at the same time. 



767. Other Methods for Plasma Cells and Mastzellen. See, inter olios 

 (in previous editions) PAPPENHEIM, Virchow's Arch., clxvi, 1901, p. 427 ; 

 BERGONZINI, Anat. Anz., 1891, p. 596 ; SCHRIDDE, Anat. Hefte, xxviii, 

 1905, p. 698 ; MAXIMOW, Arch. mik. Anat., Ixvii, 1906, p. 686 ; SCHAF- 

 FER, Centralb. Phys., xxi, 1907, p. 261 (fixation in absolute alcohol or 

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

 thionin 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). 



Fatty Substances.* 



768. Fatty Substances. The general term "fatty substances ;> is 

 used here to denote the true fats and the lipoids. 



TRUE FATS are esters of the alcohol, glycerol, with the -higher 

 fatty acids, chiefly palmitic acid, stearic acid and oleic acid. The 

 fatty acids may be " saturated " as, for instance, palmitic and stearic 

 acid, or they may be " unsaturated" as, for instance, oleic acid. 



* By Dr. W. Cramer, Imper. Cancer Research Bureau, and partly by 

 J. B. G. 



