342 SUMMARY OF CURRENT RESEARCHES RELATING TO 
flask is removed, and its contents filtered through a Diakonow’s appara- 
tus. The clear filtrate is then poured into flasks and neutralised. For 
Diakonow’s apparatus may be substituted a simple arrangement con- 
sisting of a flask, the neck of which is closed by a caoutchouc plug 
with two holes. One of the holes receives the stem of a filter ; the 
bottom of the hopper is covered with a piece of gauze upon which is 
placed a layer of glass wool and then a layer of fine sand. To the 
second hole is fitted a bent glass tube connected with an exhaust pump. 
Apparatus for Cultivating Yeasts on Plaster Blocks.* — M. H. 
Schionning has, by combining the advantages of the plaster block and 
a Hansen’s flask, devised an ingenious apparatus for obtaining pure 
ascosporous cultures of yeasts. A cylindrical block of plaster, reach- 
ing to about two-thirds up the flask, and made by mixing 2 volumes 
of plaster with 3/4 volume of water, is fixed to the bottom of the flask. 
The top of the plaster pillar is slightly hollowed for the reception of 
the yeast. The side tube having been plugged with cotton- wool, the 
apparatus is sterilised at 115° for an hour and a half. When cooled, the 
cap is removed and the culture placed in the hollow on the top of the 
pillar. The cotton-wool plug is then removed, and through the lateral 
tube sterilised water is introduced in quantity sufficient to reach half- 
way up the plaster cylinder. When the top of the pillar shines from 
imbibition of water, the whole apparatus is incubated at a temperature 
favourable for the production of spores. A piece of rubber tubing is 
previously fitted on the lateral tubulure, its free end being plugged with 
cotton-wool. By this procedure, perfectly pure cultures, quite free from 
bacteria and other contamination, are easily possible. 
Amoeba Cultures.! — Dr. 0. Casagrandi and Dr. P. Barbagallo report 
on the different kinds of media suitable for Amoeba cultures, on the re- 
action of the substrata, on the necessity for the presence of organised 
constituents therein, and on cultivable and non-cultivable Amoebae. 
With regard to fluid media, there is no doubt, they say, that Amoebae 
will develop in hay, straw, and hemp infusions, on decoction of 
faeces, and in thin albumen ; but it is practically impossible to obtain a 
pure cultivation, partly owing to the difficulty of sterilising the medium, 
and partly on account of the impurity of the inoculation material. Of 
solid media, egg-albumen with some pepton and carbonate of soda was 
found extremely serviceable. 
Media composed of the above mentioned infusions solidified with 
agar or gelatin were failures. A medium containing 5 per cent, of Fucus 
xrispus was found to possess the advantages of inhibiting the growth 
of bacteria, and of affording opportunity to the Amoebae of completing 
the stages of iheir life-cycle. 
The most suitable reaction was found to be slightly alkaline to 
neutral ; strongly alkaline or acid reaction being unfavourable. Acidity 
of the medium did not, however, prevent certain species, such as A. coli , 
from becoming acclimatised to the reaction. With regard to the asso- 
ciation of protozoa, bacteria, fungi, and yeasts, with Amoeba in the 
cultures, which some observers seem to regard as necessary and irremov- 
* Ann. de Micrographie, ix. (1897) pp. 191-8. 
f Otntralbl. Baht, u. Par , l t9 Abt., xxi. (1897) pp. 579-89. 
