264 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Separation of Micro-organisms by Centrifugal Force.* — Micro- 
organisms being composed, says M. R. Leze, of proteids, cellulose, and 
minerals, are heavier than water, hence if they float in liquids such as 
wine, cider, milk, this is probably due to the presence of gas ; the force 
necessary to move them up or down in a liquid of specific gravity hardly 
differing from that of their own protoplasmic body, must be extremely 
feeble. But this force may be augmented by setting the liquid in 
motion by means of a centrifuge. The apparatus used by the author 
were a handworked lactocrite with radius of 9 cm., giving 3600 turns, 
and a steam turbine (Burmeister’s) having a radius of 20 cm. and doing 
4000 turns. 
In the former the receivers are little tubes drawn out to a conical 
shape, with the pointed end sealed up. In the second apparatus the 
action is continuous, so that an indefinite quantity of the liquid can be 
centrifuged. 
In the hand-machine the organisms are chiefly deposited in the 
pointed ends of the receiver, in the turbine all over the sides, as a 
sticky gelatinous deposit. 
By this method liquids undergoing change of fermentation, &c., may 
be “ separated,” and the larger the organisms, the more easily is this 
effected ; thus moulds and yeasts are more easily separated than bacteria. 
By diminishing the density of the fluid centrifuging is rendered 
more easy. This may be done by heating the liquid or adding water, 
ammonia, alcohol. 
(3) Cutting-, including Imbedding and Microtomes. 
Jung’s Microtomes.f — Herr P. Schiefferdecker describes two micro- 
tomes constructed by R. Jung. The first instrument is a modification 
of the English “ Cathcart improved microtome.” It is made entirely of 
cast iron, and has the form shown in fig. 31. A strong vertical bar can 
* Comptes Rendus, cxv. (1892) pp. 1317-8. 
t Zeitschr. f. Wise. Mikr., ix. (1892) pp. 168-75. 
