WYMAN, ON THE FORMATION OF INFUSORIA. 111 
above the cork was filled with an adhesive cement d, composed 
of resin, wax, and varnish. The glass tube was bent at a right 
angle, and inserted into an iron tube e, and cemented there 
with plaster of paris c. The iron tube was filled with wires f, 
leaving only very narrow passage ways between them.* 
(2.) Others (as in Exps. 6, 12, 16 to 24, and 21 to 23 inclu- 
sive), were prepared as in fig. 2, in which the joining at a, fig. 
1, is avoided, and the iron tube is cemented directly into the 
mouth of the fiask, the neck of which is drawn out at 0, to 
render the sealing of it easy; otherwise, the conditions are the 
same as in fig. 1 
(3.) In feet experiments (as in Exps. 24 to 28, Sb 24 to 
28 inclusive), the flask, fig. 3, was sealed at the ordinary 
temperature of the room, and submerged during the period of 
the experiment in boiling water. This was the method fol- 
lowed by Needham and Spallanzani, and has the merit of 
eliminating all suspicions of error which might be supposed to 
arise from some imperfections in the joinings. 
In the first and second methods, the solution in the flask is 
boiled, and at the same time the iron tube filled with wires is 
heated to redness. While the contents are boiling, the steam 
formed, expels the air from the flask; when the boiling has 
continued long enough, the heat is withdrawn from beneath 
the flask, and, as the steam condenses, the air again enters 
through the iron tube, the red heat of which is kept up, so 
that all organisms contained in the air are burned. In both 
methods the flask is allowed to cool very slowly in order that 
the entering air may be as long as possible in passing through 
the iron tubes, and thus the destruction of its organic matter 
* An advantage in preparing the experiment in this way is, that the same 
flask may be used many times. 
