68 MOUNTING AND PREPARATION OF OBJECTS. 



before the addition of water. The proper amount 

 of staining requires considerable judgment to deter- 

 mine, but the more dilute the solution, the easier it 

 becomes and the greater the differentiation of tissue. 

 When forming an opinion, the condition of the 

 tissue, as regards its age, (embryonic tissues stain- 

 ing very readily) its hardness, the alkalinity of the 

 solution, and the magnifying power required to 

 show it properly should all be taken into consider- 

 ation. For further particulars we refer to Beale's 

 " How to Work with the Microscope," etc. ; with 

 this caution that all blue and violet staining solutions 

 are useless, unless the operator has unlimited time 

 at his disposal for the modification of the photo- 

 graphs by various methods of intensification, after 

 their direct production. 



If the sections are thin and intended for minute 

 investigation, they are removed from the carmine 

 solution by the flat spoon and placed for a short 

 time in equal parts of distilled water and alcohol, to 

 remove excess of colouring matter ; then transferred 

 to glycerine and camphor water, where they may be 

 allowed to remain for a day or two, (covered with a 

 bell jar), before mounting, in gum and glycerine. 

 If thick and only required for very low powers, after 

 removal from the carmine, they are placed in absolute 

 alcohol, for twenty-four hours. When this period has 

 elapsed each section is taken up separately by the 

 spoon, both are firmly pressed between two folds 

 of blotting paper held between the finger and thumb, 

 (no danger of injuring the specimens need be appre- 



