286 THE AMERICAN MONTHLY _ [Oct 
the protoplasm of the cell; but the 4-inch will resolve this 
mass into its constituent parts,when the needle-like bodies 
lying side by side can be made out distinctly. In the 
onion the raphides are prismatic in form, and may be 
seen scattered over the whole section; the walls of the 
cells in which they are enclosed can be clearly made out, 
and each cell contains a single crystal or raphis.” 
FoRMALIN AS A PRESERVATIVE FOR PLANTS.—The use 
of formalin for the preservation of zoological specimens 
is now very general. Its application to the preservation 
of plants and flowers, however, is quite new. The most 
satisfactory results are obtained with a 5 per cent solu- 
tion of formaldehyde, 7. e. an cighth of the strength of 
the commercial formalin, which contains 40 per cent of 
formaldehyde. The flowers and portions of plants im- 
mersed in this and kept in the dark remained intact, whilst 
the tissues became more or less translucent, showing the 
structure. After seventeen months, yellow calceolaria 
flowers had lost but little of their color, whilst a tulip 
and hyacinth had lost about 30 per cent. A pansy ex- 
posed to diffused light in a 5 per cent solution was rapid- 
ly bleached, with the exception of the lower yellow petal. 
A white tulip became translucent, but retained its extern- 
al form perfectly. The odor of mignonette was still 
perceptible after four months, nothwithstanding the pene- 
trating odor of the formalin itself. Unfortunately the 
solution soon bleached blue colors. » A blue hyacinth be- 
came opaque white in two days and translucent in six 
months. Green leaves became only slightly translucent, 
and were otherwise unchanged. In order to prevent the 
bleaching action of sunlight it was found essential to 
keep the specimens in as dark a place as possible. The 
preservative action of the formalin is due to its destroy- 
ing all external micro-organisms, and preventing the in- 
ter action of the plant-cells by contracting their proto- 
plasm.—C. A. Mitchell, London, in Science-Gossip. : 
