446 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
methylated spirit, changed as it became discoloured. These changes 
were made in the dark when the fixing solution had contained chromic 
acid. 
The anthers were preserved in a mixture of equal parts absolute 
alcohol, glycerin, and distilled water. 
B. Imbedding and Cutting. — For anthers fixed in mixtures con- 
taining chromic acid or platinic chloride, paraffin melting at 52° C. is 
hard enough. A softer paraffin can be used for anthers fixed in absolute 
alcohol. Sections 15 p, thick were cut from such material imbedded in 
paraffin melting at 45° C. 
The sections were usually floated on the slide with distilled water, 
and made to adhere by careful drying without cement. But in the case 
of anthers showing the nuclear division within the nearly mature pollen- 
grain, a cement was used of collodion and clove-oil. 
Great care must always be taken not to overheat the paraffin-ribbon 
on the slide. If the paraffin approaches the melting-point, the sections 
will he strained and their structure distorted. 
Hand-sections are apt to be broken while they are being transferred 
from a stronger to a weaker solution of alcohol. To avoid this, the 
sections were placed in a small wide-necked bottle half filled with dis- 
tilled water, on the top of which absolute alcohol had been poured 
gently. The alcohol floated for some time on the water, and the sections 
sank down through solutions of gradually increasing density until they 
lay in the pure water at the bottom. Then the alcohol was drawn off 
by a pipette. 
C. Staining. (1) Flemming's orange method for material fixed in 
Flemming's solution, Hermann's solution, or chromic acid. — For early 
stages in the development of the pollen-mother-cell, the potassium per- 
manganate was used as a mordant both before and after the treatment 
with safranin. The safranin and gentian-violet solutions were also of 
double the usual strength for these stages. For later ones — as the first 
nuclear division in the pollen-mother-cell — the ordinary treatment was 
sufficient. 
(2) Mayer's hsemalumfor chromic material. — The sections were placed 
for half an hour in a 0 • 5 per cent, solution of ferric chloride in water, 
rinsed, and transferred to Mayer’s hsemalum, nearly full strength. They 
usually took about 2 hours to stain to the right depth. If the sections 
were kept alkaline by rinsing in hard water and by the use of neutral 
alcohols, they were of a brilliant blue, and very permanent. 
(3) Mayer's hsemalum for absolute alcohol material. — The sections 
were treated as above, but with a 0 • 1 per cent, solution of ferric chloride 
for half an hour, and 10 per cent, solution of Mayer’s liasmalum in 
0*1 per cent, solution of potash-alum for about 12 hours. 
(4) Methyl-green and acid fuchsin for alcohol material. — These 
colours were used in aqueous solution ; their proportion varied to suit 
different stages. 
(5) Henaut's lisematoxylic eosin for alcohol material. (See this 
Journal, 1896, p. 699.) 
Agar as Medium for Bacteriological Examination of Water.* — 
According to Herr F. Hesse, agar possesses several advantages over 
* Centralbl. Bakt. u. Par., l tc Abt., xxi. (1S97) pp. 932-7. 
