THE PREPARATION AND MOUNTING OF 

 DOUBLE STAININGS.* 



There is no art of the microscopist more beautiful and inter- 

 esting than that of bleaching and re-coloring vegetable tissues. 

 In no other way can the wonderful processes of plant growth be 

 made manifest under the microscope. Therefore, any sugges- 

 tions tending to simplify the art and make it more generally 

 practicable, will be of interest to all workers in microscopic 

 preparations. In my experiments with double staining I have 

 found that different colors, or at least different pigments, vary 

 greatly in the activity or penetrating power with which they 

 affect vegetable substances. Thus, an object prepared for stain- 

 ing may be left in a strong solution of carmine for a day without 

 having all its parts colored ; whereas in a logwood or analine 

 dye of equal strength, it would be colored perfectly opaque in 

 less than an hour. By taking advantage of this fact and 

 immersing objects, first in the color having the slowest action, 

 then in another of greater activity, and so on, double or even 

 multiple staining becomes a simple process, instead of the very 

 difficult and complicated one which has been published in our 

 magazines. 



I will give the general details of the operation as I have now 

 practised it for some little time. I do not claim that exactly the 

 same formula will answer for all kinds of plant specimens, or 

 that all the colors given below should be used in all cases. I 

 merely give a general formula, which each operator will find it 

 necessary to vary somewhat according to the results of his 

 experimenting. If I succeed in stimulating others to more 

 detailed work, by showing how simple the process is in most 

 cases, I will have accomplished my purpose. All vegetable 

 preparations, whether parts of leaves or sections of stems, should 

 first be fully decolorized in the common chlorinated soda solution, 



* A Paper read before the National Microscopical Congress, held at Buffalo, 

 August, 1878, and published in its Proceedings. 



