20 BOTANICAL MICROTECHNIQUE. 



a large quantity of the staining solution. This staining 

 should therefore be carried on, not on the slide, but in 

 dishes or beakers which will contain at least a half liter of 

 fluid ; and not too many of the objects to be stained should 

 be placed in each. Finally, the rapidity of the staining may 

 be hastened by agitating the fluid. 



VII. Methods of Fixing and Staining. 



2p. In the investigation of the various plasmatic constit- 

 uents of the protoplasm, which are largely colorless and 

 commonly distinguished only by slight differences in refrac- 

 tive power, it is often impossible in difficult cases to reach 

 positive results with living material. But there may be 

 used with the best results the methods of fixing and staining 

 devised chiefly by anatomists and zoologists. These have 

 already led to such important results in the study of the 

 vegetable organism that not the least doubt remains as to 

 their applicability in botanical investigations. Yet, on the 

 other hand, it cannot at all be maintained that the study of 

 living material should now be wholly given up. On the 

 contrary, it should be used, whenever at all possible, for the 

 control and explanation of the results obtained from stained 

 preparations. 



30. The purpose of fixing is to kill the object in such a 

 way as to preserve its structural relations as completely as 

 possible after the removal of the fixing medium. 



It is the object of staining to so color certain particular 

 cell-constituents of the fixed preparations, which are to be 

 specially studied, that they shall be sharply differentiated 

 from their surroundings, so that their confusion with other 

 cell-constituents may be prevented. 



We possess at present an innumerable lot of fixing and 

 staining methods, and already the most various new or 

 long-known organic and inorganic compounds have been 

 tested with reference to their usefulness as fixing and stain- 

 ing media. While most of these experiments have led to 

 no new conclusions concerning the morphology of the cell, 

 and many methods warmly recommended by their discov- 



