130 BACTERIOLOGY. 



may be rinsed with water, and stained for half an hour 

 with Weigert's picrocarmine. From this they are again 

 removed to water, then to alcohol, clove-oil, and 

 Canada balsam. 



The method of Gram is much more satisfactory (p. 56, 

 Plate XII., Fig. 2). Sections should be examined with 

 and without a contrast stain. The after-stain most com- 

 monly employed is eosin. The sections after the process 

 of decolorisation should be placed in a weak alcoholic 

 solution of eosin (two or three drops of a concentrated 

 alcoholic solution added to a watch-glass full of alcohol), 

 till stained a delicate pink. They are then rinsed in 

 fresh alcohol, treated with clove-oil, and preserved in 

 Canada balsam. 



Sections containing cocci of osteomyelitis may be after- 

 stained with weak solution of vesuvin. Safranine and 

 picro-lithium- carmine may also be used as contrast stains 



( P . 5 8). 



Nuclear stains, such as carmine, haematoxylin, may also 

 be employed. Sections may be left one minute in 

 Grenacher's solution, then washed out in weakly acidulated 

 alcohol (2 1000) ; and finally treated in the usual way, 

 with alcohol, oil of cloves, and balsam. 



Sections containing micrococcns tetragonus are best stained 

 with Gram's method and eosin (Plate XII., Fig. i), but 

 they may also be treated by the method of Friedlander, to 

 demonstrate their capsules (p. 135). 



To stain the cocci of rabbit- septiccemia and of chicken- 

 cholera in the tissues, place the sections twenty-four hours 

 in Loffler's solution, wash in water faintly acidulated with 

 acetic acid, then treat with alcohol, oil of cloves, and 

 balsam. Babes recommends staining the microbe of 

 chicken cholera by immersing the sections for twenty- 

 four hours in a concentrated solution of methyl-violet B, 

 or of safranine.* 



* Cornil and Babes, Les Bacteries, 1885, p. 208. 



