TECHNIQUE. 49 



Cover-glass preparations or tissues, previously 

 rinsed in distilled water after fixing, should be placed 

 in solution No. 1 over night, after which they are 

 rinsed in distilled water and immersed in solution 

 No. 2 for from 6 to 24 hours and in the case of 

 sections as long as 36 hours. They are then rinsed 

 in distilled water and decolorized in solution No. 1, 

 this process being controlled by observation under the 

 microscope, until the nucleus is well differentiated, 

 the chromatin staining a deep blue-black and the 

 cytoplasm a light gray; the preparations are then 

 washed in running water for half an hour and rinsed 

 in 50 per cent., 70 per cent., 90 per cent, and absolute 

 alcohol, cleared in xylol, and mounted in Canada 

 balsam. 



This method requires considerable experience in 

 order to obtain the best results, but may be said to 

 be the best method we possess for the study of the 

 structural details of amoeba?. 



The Giemsa Stain. Very beautiful specimens 

 may be obtained by this method. Its chief objection 

 is that the method of preparation is so complicated 

 and requires so much care that it can only be used 

 in a well equipped laboratory. However, a reliable 

 Giemsa stain may be obtained from Grubler. The 

 following is the method of preparation of this stain 

 and of its use in staining amoebse : 



