GOG SUMMARY OF CURRENT RESEARCHES RELATING TO 



lime, 2 oz. ; common soda, 3 oz. ; water, 2 pints. Mix the chloride of 

 lime with half the water, and the soda with the other half, then mix the 

 two solutions and let settle in a well-corked bottle ; pour off the clear 

 liquid for nso, and keep in stoppered bottles. 



Pour the spirit and water from the fern and rej^lacc it with the 

 bleaching fluid, and put in a strong light if you wish to hasten tho 

 process. Look at them often, and when there is no longer any appear- 

 ance of chlorophyll in the sporangia or in the leaf, the bleaching has 

 gone far enough. It is not always safe to wait for a stout mid-vein to 

 become perfectly clear, for a very little over-bleaching may injure or 

 ruin the fern. In some cases, however, it may be necessary to change 

 the bleaching fluid two or three times. 



AV'hen the bleaching is completed, remove to a liberal supply of soft 

 water and change frequently until no trace of chlorine remains, for if tho 

 chlorine be not quite removed the staining will bo a failure. Then 

 harden the material in alcohol. 



For staining epidermal structure the author advises alum-carmine and 

 methyl-green in the proportion of one drop of methyl-green to ten drops 

 of alum-carmine. The time reqiiired is variable. The spores and cases 

 stain green and the leaf red ; sometimes the larger veins also take on the 

 green. If stained too long the red will supplant the green. Transfer 

 to at least tuo ounces of water and soak for three or more hours to 

 remove the alum. 



For thick-leaved ferns, and for showing the fibro-vascular system 

 and sporangia, the following procedure will be found more satisfactory : 

 To forty drops of borax-carmine add one drop of methyl-green. Tho 

 time required is longer than with alum-carmine. Then soak in water as 

 before. A saturated solution of ammonia acetate used as a mordant will 

 heighten the colour a trifle. 



The best medium for mounting is glycerin jelly made after Kaiser's 

 formula, with additional gelatin to give it hardness. First transfer to a 

 mixture of equal parts of glycerin and alcohol. Then heat the glycerin 

 jelly in a water-bath, keeping hot while using to prevent air-bubbles. 

 With a glass rod place a few drops on the slide with or without a cell ; 

 a cell makes a better finish. Place the ferns in the glycerin jelly, add 

 a few drops, and pour off to get rid of the alcohol and glycerin, replace 

 what is jioured off and examine with a dissecting Microscope for air- 

 bubbles, which must be removed before tlie cover is applied. Breathe 

 on the cover and apply a droj) or two of hot glycerin jelly, then breathe 

 on the slide and impose the cover. 



Another way is to let the glycerin jelly harden on the slide with tho 

 fern on it and afterwards apply some hot jelly to the surface before 

 putting on the cover. Wood sections may be stained and mounted in 

 the foregoing manner. 



Application of Lactic Acid to the Examination of Algae.* — Herr 

 G. Lagerheim recommends the use of lactic aci^ for restoring the turgidity 

 to dry algrc. The acid is used in a concentrated semi-fluid form. The 

 dry alga is first softened in water, and then placed in small pieces in 

 a few drops of the acid on a glass slide, and heated until small bubbles 

 make their appearance in the acid. The alga must be prevented from 

 becoming too fluid and flowing away by heaping up with a knife. After 



* Hedwigia, xxvii. (1888) pp. 58-9. 



