1S89.] MICROSCOPICAL JOURNAL. 79 



it up well before applying tlie pipette, the stuff" in mounting will be so 

 separated on the slide that he will be sure to have a number of desmids 

 freely exposed to view. For the purposes of study it doesn't matter how 

 much dirt there is on the slide so long as the desmids are free from it. 



Either carbolic acid or Stokes' fluid preserves them well. The lat- 

 ter comes already prepared, or it ma}- be made up by the druggist ac- 

 cording to the formula, and the desmids are to be transferred to it, or 

 the small phial containing them is to have almost all the water poured 

 oft' and then to be refilled with the fluid. But if the carbolic acid is 

 used two or three drops of the strongest solution is enough for a four or 

 six ounce bottle, which ought to be well shaken after it is added, and 

 the material ought not to be more than half an inch deep, otherwise 

 it may not keep. I do not find much difterence between the two pre- 

 servative media. Stokes' fluid gives a brighter field and keeps the ■ 

 chlorophyll perhaps a trifle greener, but it causes it to shrink rather 

 more. However, both are excellent, and the student may consider him- 

 self fortunate in having two such good fluids to choose between. For 

 years it was a serious question to get anything that would do at all. 



As to the mounting a shallow ring is necessary, and shellac answers 

 admirably. Brown's cement may also be used for this purpose, but it 

 takes longer to make the cell. When the ring is thoroughly dry, brush 

 it over lightly on the turn-table with the rubber cement. Wait a sec- 

 ond till it has partially set. Then with the pipette take up a few drops 

 of the material from the carbolized water qr Stokes' fluid and fill the 

 cell, tilting the slide so that the Jluid touches the shellac ring all 

 round and rises above it in the centre. Now apply the cover, in- 

 clining it a little to one side and letting it fall gradually so as not to en- 

 close any air-bubbles. Take up the superfluous fluid, which will be 

 forced out, with a bit of blotting paper, press down the cover evenly all 

 round bv the needle or end of the holder, and apply a thin coat of the 

 cement i-ight at the junction of cell and cover. After a minute or so 

 another coat, this time wider, taking in more of the cell ring and a little 

 of the cover. When this has had time to stiflen give it a third and 

 thicker coat. And the next day go over it as much as you like and 

 finish oft' smoothly, without any fear that the cement will run in, and 

 vou have a mount which will last and be well adapted for study. 



Notices of New Methods — IX. 



By GEORGE C. FREEBORN, M. D. 



INSTRUCTOR IN NORMAL HISTOLOGY, COLLEGE OF PHYSCIANS AND SURGEONS, NEW YORK. 



Some Ne\v Dyes for Histological ^Vo^k. Zachokke. Zeitschr. 

 f. Wiss. Mikros, v., iSSS, p. 446. 



Benzopurpurin B. — This dye comes in the form of an amorphous 

 brownish powder, freely soluble in water. The solution is a cinnabar- 

 red color and gives a corresponding colored stain. The solution stains 

 in a few moments, giving a diffuse stain, like acid fuchsin. The cel- 

 loidin stains first, then the connective tissue, and finally the nuclei. 

 The color is not changed by water, glycerine, acidulated alcohol, dilute 

 solutions of hydric acetate or potassa solutions ; acids darken the color. 

 Alcohol extracts the color from the celloidin, also slightly from the 

 protoplasm and nuclei, while the connective tissue remains intensely 



