124 PRACTICAL BACTERIOLOGY. 



(1) Aniline water solution of gentian violet, or of 

 methyl violet, or of fuchsine. The sections remain in 

 one of these solutions for from two to ten minutes. 

 They are then taken out with the platinum spatula, 

 dried and put into 



(2) Twenty per cent nitric acid ; in this they only 

 remain for a few seconds, if the sections are thin 

 enough, generally until the coloration is quite 

 changed. If the sections are very unevenly cut, 

 no notice must be taken of the thicker parts, but 

 before the colour is completely changed in these 

 places, the sections must be taken out with the 

 spatyla, the superfluous acid removed with, blotting 

 paper, and placed in 



clumsy. The usual steel needles and spatulse have the dis- 

 advantage that the metal is quickly attacked by acids, 

 especially by nitric acid, and this not only prevents their 

 being used for any length of time, but causes black sub- 

 stances to be precipitated on the section, which, as they 

 cannot be got rid of, often render the preparation quite 

 useless. Platinum spatulse have none of these drawbacks, 

 but as they are not easy to obtain in the shape which is 

 desirable, I give here a very easy method of making them, so 

 that the student may be able to make one himself of any 

 shape or size that he wishes. A piece in the shape of a shovel 

 or scoop, and of the required size is cut out of a strong piece 

 of sheet platinum, a pointed handle of about one cm. in 

 length being left at one end. This handle is then fused into 

 a fairly strong glass rod. It can then be bent into a very 

 convenient form. 



