WEJGERT'S NEW METHOD. 369 



For details of the numerous mordants that were unsuccess- 

 fully tried, see the paper quoted. 



Wolters's axis-cylinder stain is given in 726. 



701. MEBCIEE (Zeit.f. wiss. Mik., vii, 4, 1891, p. 480) has a modification 

 which consists in adding glycerin to the stain (which possibly may serve to 

 usefully increase its penetrating power), and employing after the usual dif- 

 ferentiating fluid a second differentiating fluid composed of 2 parts of 10 per 

 cent, potash solution, 10 parts of water, and 1 part of sulphuric ether. I 

 cannot find that this process has been recommended by any other worker. 



702. HAUG'S modification of Weigert's process is given in 755. 



703. WEIGERT'S New Method (Deutsche med. Wochenschr., 

 42, 1891, p. 1184; Zeit. f. wiss. Mik., viii, 3, 1891, p. 392). 

 The material is to be hardened in bichromate and imbedded 

 in celloidin in the usual way. The hardened blocks of cel- 

 loidin are brought into a mixture of equal parts of a cold 

 saturated solution of neutral acetate of copper and 10 percent, 

 aqueous solution of potassio-tartrate of sodium (C 4 H 4 6 KNa 

 + 4H 2 0, salt of Seignette). They are left in the mixture for 

 twenty-four hours in an incubator. (Large specimens [Pons] 

 will require forty-eight hours, the mixture being changed for 

 fresh at the end of twenty-four hours.) They are then brought 

 for twenty-four hours into aqueous solution of neutral acetate 

 of copper, either saturated or diluted with 1 volume of water, 

 being kept as before in the incubator. They are then rinsed 

 with water and brought into 80 per cent, alcohol, in which 

 they may either remain till wanted or be cut after half an 

 hour. 



The sections are stained for from four to twenty-four hours 

 at the temperature of the room in a freshly prepared mixture 

 of 9 vols. of (A) a mixture of 7 c.c. of saturated aqueous solu- 

 tion of carbonate of lithium with 93 c.c. of water, and 1 vol. of 

 (B) a solution of 1 grm. of haematoxylin in 10 c.c. of alcohol (A 

 and B may be kept in stock, but A must not be too old). The 

 sections must be loose ones, not such as have been seriated in 

 celloidin, and must not be thicker than 0'025 mm. The stain 

 is poured off and the sections are washed in several changes 

 of water poured on to them. They are then treated with 90 

 per cent, alcohol followed by carbolic-acid-and-xylol mixture 

 (for a short time only), or by a mixture of 2 parts of anilin oil 

 with 1 of xylol, then pure xylol and xylol balsam (not chloro- 

 form balsam, which injures the stain). 



24 



