THE MIcROSCOPE. 197 
When the paraffin is sufficiently hard, the microtome is 
clamped to the table and the operator is seated on a chair before 
it. To the right is a large soup plate and a saucer, each 
filled with equal parts of alcohol and water. A chamois or 
piece of soft linen is near at hand. The knife is firmly grasped 
in the hand and dipped in the plate, carrying in its upper con- 
cave surface a quantity of the dilute alcohol to the surface of 
the microtome. <A few turns of the microtome screw raises the 
paraffin, when a thick slice is cut off. This is repeated until the 
knife has passed once through the tissue. 
The knife should be pushed obliquely from point to heel; 
a direction forward and to the left. After each section the 
blade should be wiped on the chamois or linen, to remove any 
pieces of the embedding mixture from its edge. 
A partial revolution of the milled head raises the embedded 
tissue above the surface of the microtome; the knife is dipped 
in the dilute alcohol and a quantity of it carried to the surface 
of the microtome, which is kept flooded all the time; a rapid 
push of the knife removes a section which is carried into the 
saucer and floated off; the section clears itself from the em- 
bedding mixture owing to the layer of mucilage coating its sur- 
face and falls to the bottom of the dish while the oily paraffin 
remains at the top, to be floated off. 
—_—__—¢ e >—__—_ 
WHAT IS THE AMERICAN FORM OF PARAMACIUM 
AURELIA ? 
DR. ALFRED C. STOKES. 
Mes statements as to the results of all observations, micro- 
i scopical especially, and whatever their source, must justly 
and necessarily be received with some hesitation until confirmed 
by an independent worker. The declarations of James Clark, 
Carter or Leidy, who have become illustrious as learned natu- 
ralists, accurate observers and conscientious narrators of scien- 
tific truths, are usually accepted without :that semi-reluctant 
feeling that the statement is remarkable and that one would 
like to verify it, probably because they have proved themselves 
to be so perfectly honest. But no human being is infallible ex- 
