STAINS. 



1S9 



Wash the sections in distilled water and tlicn 

 in tap-water. Stain ( nntil \ery bhick) in water 

 containing [ per cent haenialoxylin. Differen- 

 tiate in 30 per cent acetic-acid water witli care- 

 lul watclnng, or in more dilute acid, or in \-erv 

 ddiite (I : 20) liquor ferri, if it is to he followed 

 hy acid fuclisin as a contrast stain. (Verhandl. 

 d. :\nat. Gessellsch , 1X03, J^na, Guslav Fischer.) 



HciJciihain's Inni llacinatuxylin. 

 Mordant the sections from one-half hour to 

 12 hours in a 2.5 per cent waler\- solution of iron 

 alum (annnoino-fcrric sulphate ( NMO^ Fe^ 

 iSO,')i dissoKed cold). This salt conies in 

 violet crystals. Yellow or .green crystals should 

 he rejected. Rinse well in water. Stain in 

 water containing 0.5 per cent of hacmato.x_\'lin. 

 Rinse, expose again to the iron-alnm solution, 

 watching the differentiation under the nnero- 

 scope, the examination being made in tap- water. 

 Wdien properly differentiated wash 15 to 45 nnn- 

 utes in running water. Itehydrate, clear only 

 with xylol, and mount in xylol balsam. The 

 mordant docs not keep indefinitely, but is said 

 to retain its jiroperties for some time (Dod.ge), 



Scliaffncr's Sufruniii Picro-iiii^roslii. 



'bhe slides are stained for a few minutes in 

 luilin-safraniii made as follows. 



(l ) Anil in water 50 



.Saturated alcoholic (05 per 

 cent) se^lution of safranin.... 50 



Rinse quickly in water. They arc then stained 

 in (2). 



(2 ) 1 )istillcd water roo 



Picric acid thoroughly dissolved 



in the above i 



Then arid nigrosin i 



Rinse in water, wash rapiilly in 95 per cent al- 

 cohol, dehy<lrate, and mount in balsam 



Mdhicliilc Green. 



For plant tissues, as well as animal tissues, 

 this ma.\ be used as a contrast stain, follow- 

 ing carhol-fuchsin. It is dissolved in anilin 

 (i : 1000) and used fresh; generally the ex- 

 posure to it should be for only a very brief 

 period, /. e., I to ,5 minutes. If not fresh, much 

 longer exposures are required. 



CbEAXING CO\'KR-GI-ASSICS 1-(JR FI^AOF.LLA STAIXS. 



Van Kriiieng-eni recommends boiling in a mixttire of water lori cc, concen- 

 trated sulphnric acid 60 cc, potassium bichromate 60 .grants. The covers are 

 afterward tlioroughly washed, first in water and then in aljsohite alcohol. They 

 are set on edge and dried nnder a bell-jar. 



Loefifler recommends heating co\-ers in concentrated snlplmric acid. The)- are 

 then washed in distilled water and pttt into alcohol-ammonia, from which they are 

 wiped with a very clean linen cloth. 



Covers cleaned in the ordinar}- wa}- ma}- be freed from fat by passing them 

 through a Bnnsen flame immediateh' before ttsing. 



FLAGKFFA .STAININC;. 



There is no easy road to sttccess. Some of the common stones of stitmbling 

 are (i) oil\- or otherwise dirt}- covers ; (2) citlttires nnsnited either b}- age or b}- 

 composition of the meditim ; (3) the casting off of flagella on dilution or during 

 the slow dr}-ing of the fluid on the cover ; (4) an une\-en or too copious distribution 

 of the organisms on the cover ; (5) imperfect mordanting ; (6) excessive mor- 

 danting ; (7) understaining ; (8) overstaining ; (g) precipitates on the cover-glass 

 during some .stage in tlie process. 



If clean covers are used, if the bacteria are deri\-ed from \-oting moist agar cult- 

 ures, if a \-er}- small quantit}' of such culture is put into a large drop of well aerated 

 water, or, better, into a test-tube or watch-glass containing 5 or 10 cc. of water, and a 

 tinv quantity of this dilution is taken on a platinum needle and defth' swept over 

 the whole cover ; or if the needle is touched to the bacterial fluid and then totiched 



