CHAPTER XV 7. 195 



mik. Anat,, xlix, 1897, p. 772 ; liii, 1898, p. 237 ; Zeit. wiss. Zoo/., 

 Ixvi, 1899, p. 361 ; and Encyd. mik. Technik, 1903, p. 825, and 

 1910, p. 108.) He omits the peroxide, the hydrochloric acid, and 

 the cooling. Bethe (Zeit. tciss. Mik., xvii, 1900, p. 21) does not 

 approve of these modifications. 



Further modifications of the molybdenum method have been 

 published by LEONTOWITSCH (Intern. Monatsschr. Anat., xviii, 1901, 

 p. 142). 



MICHAILOW (Zeit. wiss. Mik., xxvii, 1910, p. 19) adds to 8 per cent, 

 solution of molybdate 0-5 per cent, of formalin, leaves the objects 

 in a large quantity of it (filtered) for twenty-four hours at 37 C., 

 washes with warm water, and passes through alcohol and xylol into 

 xylol-damar (not balsam). 



See also SCHMIDT (Arch. Ges. Phys., ciii, 1906, p. 522). 



HARRIS (Philadelphia Medical Journ., May 14th, 1898), after 

 staining, rinses with water, and brings into a saturated solution of 

 either ferrocyanide or ferricyanide of potassium which has been 

 cooled to within a few degrees of zero (a trace of osmic acid may be 

 added to prevent maceration). They remain therein for three to 

 twenty-four hours, and are then washed in distilled water for an 

 hour, and are dehydrated in absolute alcohol kept at a low tempera- 

 ture, cleared in xylol or cedar oil, and imbedded in paraffin. 



345. Impregnation of Epithelia, Lymph-spaces, etc. (DOGIEL, 

 Arch. mik. Anat., xxxiii, 1889, pp. 440 et seq.). Suitable pieces of 

 tissue (thin membrane by preference) are brought fresh into a 

 4 per cent, solution of methylen blue in physiological salt solution 

 (in the Encyd. mik. Technik, 1903, p. 827, Dogiel gives the strength 

 of the methylen blue as J to 1 per cent.). After a few minutes 

 therein they are brought into saturated solution of picrate of 

 ammonia, soaked therein for half an hour or more, then washed in 

 fresh picrate of ammonia solution, and examined in dilute glycerin. 



If it be wished only to demonstrate the outlines of endotheliurn 

 cells, the bath in the stain should be a short one, not longer than 

 ten minutes in general ; whilst if it be desired to obtain an impregna- 

 tion of ground-substance of tissue, so as to have a negative image of 

 juice canals or other spaces, the staining should be prolonged to 

 fifteen or thirty minutes. 



If it be desired to preserve the preparations permanently, they 

 had better be mounted in glycerin saturated with picrate of ammonia, 

 or (Encyd., 1910, ii, p. 110) fixed with ammonium molybdate and 

 a trace of osmium. 



132 



