562 SUMMARY OF CURRENT RESEARCHES RELATING TO 
collodion of commerce does not form a sufficiently homogeneous pellicle ; 
and the author recommends the following preparation : — gun-cotton 
4 grm., 90 per cent, alcohol 10 grm., sulphuric ether 32 grm., castor 
oil 2 grm., lactic acid 2 grm. The lactic acid insures clarifying of the 
hyphae. When the ether has evaporated, this collodion leaves behind a 
remarkably delicate pellicle, which must be carefully removed, carrying 
the fungus along with it. The cellulose is then again dissolved off by a 
drop of a mixture of 90 per cent, alcohol and ether, the glass slide heated, 
and a small piece of glycerin gelatin placed on the preparation ; this at 
once liquefies, and incloses within it the fungus with all its parts in 
their natural position. 
Preparing and Examining Hyphomycetes.* — One of the simplest 
methods for examining spore-formation on aerial hyphae is, says Dr. 
Unna, to use a cell-slide and to fill the cell with nutrient agar. When 
the medium has set, one-half is to be cut out and the fungi grown on the 
remaining half. Under these conditions pretty high powers may be 
used for examining the fungi and their growth. But a more effective and 
even simpler method is to grow the fungi in a test-tube and observe them 
in situ. On obliquely set media a cultivation track is made not only 
along the middle, but also along the edge where it joins the glass. This 
allows, especially if the glass be very thin, the cultivation to be well 
seen. This method allows of numerous modifications ; for example, the 
cultivation having grown up, most of the medium may be got rid of 
by gently heating it, and then when liquefied, pouring it off, thus leaving 
only a thin layer, on which the growth is left behind. These “ minimal 
cultivations ” are very superior to all other methods for observing the 
various stages of growth, and a pure cultivation may be thus kept under 
observation for weeks or months. 
The cultivations may be fixed and stained by the following method. 
The test-tube is filled in with the following mixture: — gelatin 1, liq. 
ammon. fort, and spirit equal parts 25*0, glycerin 15*0, distilled water 
35*0. This moistens the fungi, drives off air-bubbles, renders the 
minimal cultivation quite transparent, and turns it into a permanent 
cultivation. 
If the cultivation is to be stained, it is previously treated with a 
watery spirituous solution of some basic anilin dye ; it is next washed 
with weak spirit, and then the glass vessel is filled up with salt solution 
or acetate of potash. 
The cultivation is cleared up and fixed by treating it with alcohol 
and then with petroleum, to which a few drops of nitro-benzol have 
been added to prevent fluorescence. 
While the natural growth of fungi is better observed in minimal cul- 
tivations, stained preparations are more conveniently obtained from 
slide cultivations, and very minute details are given by the author as to 
the manner in which he proceeds. The great difficulty appears to be to 
get rid of the nutrient medium, as this absorbs anilin pigments more 
easily than the fungi to be stained. However, by treating the culti- 
vation with a 20-30 per cent, potash solution and warming moderately 
the medium is so softened that it may be squeezed away from the 
Centralbl. f. Bakteriol. u. Parasitenk., x : . (1892) pp. 4-9, 40-44. 
