THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YOL. I. 



New Yoek, May, 1880. 



No. 5. 



Double-staining of Yegetable 

 Tissues. 



Having used a number of dyes 

 in double-staining vegetable tissues, 

 the conclusion I have arrived at is, 

 that no rules can be given which 

 will ensure success in every case. 

 The process is quite familiar to 

 every working microscopist, but I 

 have been somewhat surprised at 

 the limited number who have fairly 

 succeeded in differentiating the 

 tissues. 



In my own experience, I have 

 met with some sections which ob- 

 stinately refuse to act as they should, 

 under the operation of the two 

 colors, but even these, with patient 

 manipulation, can be induced to 

 show some results, even though they 

 may not exhibit that sharpness and 

 purity which it is the aim and ob- 

 ject of the mounter to obtain. 



I think that a writer in Science 

 Gossip has come nearer to the true 

 laws governing the process, than any 

 one who has written on the subject ; 

 he has, at least, indicated the direc- 

 tion in which the practical worker 

 must look to attain success. My 

 own theory differs slightly from his, 

 and consequently my process varies 

 somewhat, but in the main it is the 

 same. 



It seems to me that the capacity 

 for staining tissue resides more in 

 the colors than in the tissue itself. 

 A stain may be permanent, unless 

 it is driven out. It may be driven 

 out by some solvent, by some bleach- 

 ing process, or lastly by some other 



color. Some tissues hold the stain 

 more tenaciously than others, prob- 

 ably on account of their varying 

 density. Thus the spiral and bass- 

 cells will retain a color longer un- 

 der the influence of a solvent, than 

 the softer and more open parenchy- 

 mal cells. I endeavor to take ad- 

 vantage of this property, by giving 

 the whole tissue all of one color 

 that it can be induced to take, and 

 then driving it out of the paren- 

 chymal tissue by a stronger color, 

 stopping the process at the moment 

 when the second color has com- 

 pletely replaced the first color in 

 the soft tissues, and before it has 

 begun to act upon the more dense 

 cells. If a section be stained with 

 roseine, and then be left long 

 enough in a solution of Nicholson's 

 blue, the whole section will be blue, 

 with no visible trace of red. If it 

 be taken out before the blue has 

 permeated the entire tissue, the red 

 will show, in some parts, quite clear 

 and well-defined among the sur- 

 rounding blue tissues. Following 

 out this principle, that exact point 

 must be determined when the blue 

 has gone far enough. 



In practice, I carry out my theory 

 as follows. I use a two-grain, neu- 

 tral solution of eosin, and in this I 

 preserve my prepared sections until 

 I am ready to use them. They 

 keep perfectly well in this solution, 

 and are always ready to undergo 

 the final process, which requires but 

 a very short time before they can 

 be placed, fullv finished, under the 



