APPENDIX. 413 



from Unna's method. The preparations are stained in methylene blue, 

 and up to the stage of the washing with lithium carbonate are treated 

 exactly as above The section is then spread out on a cover glass, and 

 the moisture is allowed to run off the edge on to blotting-paper, the upper 

 surface being carefully wiped with a cloth. With a balloon syringe a stream 

 of air is then directed down on to the section as it lies on the cover glass, 

 and beginning at the centre of the section gradually driving the water 

 towards the margins, and then on to the cover glass, whence it may be 

 removed by scraps of blotting-paper. The sections are then placed on a plate 

 of glass which is gently warmed over a lamp to the body temperature, the 

 sections gradually becoming transparent and glassy, the heating is continued 

 for about five minutes after this occurs, after which they are treated with 

 terebene, then with xylol, and mounted in balsam in the usual fashion. 

 For other methods the reader is referred to works specially devoted to the 

 treatment of this subject. 



To demonstrate Tubercle bacilli in Milk. 



To demonstrate tubercle bacilli in tuberculous milk the best plan is to 

 pass the milk through a centrifugal apparatus and to take the sediment for 

 examination, as almost the whole of the bacilli that were originally in the 

 milk will be found along with the mucus and solid particles in this sediment. 

 Where it is not possible to obtain the use of such apparatus the milk should 

 be allowed to stand for from twelve to twenty-four hours in a glass "sepa- 

 rator " such as is used by chemists or in a conical or funnel-shaped vessel 

 surrounded by ice. The sediment with the contained bacilli is drawn off 

 from the separator by the tap placed at its lower part, or the cream and the 

 upper layers of the milk may be carefully removed by means of a siphon, 

 then with a pipette a few drops of the milk from the bottom of the funnel 

 are taken, dried on a cover glass, and examined in the ordinary way. In 

 place of the separator or other funnel-shaped vessel, I have used, at Mr. 

 Coghill's suggestion, a long wide burette in which to place the milk. In 

 drawing off the sediment from the separator or burette the first few drops 

 are rejected, the fluid from immediately above the stop-cock, which contains 

 most of the bacilli, being taken.* 



To demonstrate Flagella on Bacilli. 



Make a potato broth composed of two parts cooked potato mashed and 

 boiled in ten parts of distilled water ; carefully sterilize ; on this make a 

 cultivation of the required organism. A drop of the culture is then diluted 

 from five to ten times with distilled water. If the organisms will not 

 grow on this potato broth they may be cultivated in meat bouillon, which 

 must be diluted forty or fifty times before it is used for microscopic ex- 

 amination, or on gelatine, which must be diluted about one hundred 

 times. A drop of the diluted fluid is spread on a cover glass ; on this 

 a drop of 10 per cent, alcohol is allowed to fall ; the whole is dried in 

 the open air or in a warm room at a temperature of 40 C. ; the bacilli are 

 then stained in a solution made up as follows : 10 per cent, tannin solution 

 20 parts, water 80 parts, cold saturated solution of sulphate of iron 5 parts, 

 fuchsin or methyl violet I part ; to this mixture a drop of hydrochloric acid 

 in some cases, or of an alkaline solution in others, will bring out flagella 

 most beautifully. Acetic or sulphuric acid may be used. Cholera bacillus, 

 vibrio Metschnikoff, spirillum rubrum, spirillum concentricum, and proteus 



