ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
535 
heated for some time to boiling-point in a water-bath in order to drive 
out the air from the agar. After this they are sterilized for five minutes 
at 120° C., and allowed to set in oblique position. 
Simple Method for sterilizing Catgut.* — Mr. G. R. Fowler sterilizes 
commercial catgut by boiling it for an hour in 97 per cent, alcohol. The 
control experiments were made with anthrax and suppuration cocci. It 
was found that catgut which had been soaked in these germs was ren- 
dered perfectly sterile in an hour. 
(2) Preparing 1 Objects. 
Dehydrating Apparatus.f — Mr. M. B. Thomas writes: — “A very 
convenient form of Schultze’s dehydrating apparatus can be made as 
follows : — In a 9 x 9 in. Whittall-Tatum museum jar a disc of plaster 
of Paris is supported about 2 cm. from the top by means of legs made 
of glass rods (fig. 66, A and C). The disc is perforated to allow tubes 
of sizes varying from 2 to 4 cm. 
in diameter to pass through. FlG - 
These are the so-called dehy- 
drating tubes (fig. 66, B). The 
plaster of Paris diaphragm can be 
made by first making a mould of 
the desirod size with a paper 
bottom and a cardboard hoop for 
the outside. This must be placed 
on a level surface. The plaster 
of Paris is then softened with 
water and poured into the mould 
to about the depth of 1^ cm. 
While it is yet soft the three 
legs can be inserted near the 
edge, and holes for the dehy- 
drating tubes cut in the disc with 
a knife, or pressed out with glass 
tubing of convenient size. When 
the plaster of Paris is thoroughly dry the hoop can be removed and the 
disc placed in position in the jar. 
The jar is then filled with alcohol to about 2 cm. of the under side of 
the disc. The dehydrating tubes should be about 12 cm. long, and can 
be made by cutting off the bottom of large test-tubes. At the bottom is 
placed a diaphragm of chamois skin, which can be fastened in place by 
means of a spring made of steel wire, and forced inside of the chamois 
skin in the tube, thus pressing the former firmly against the latter 
(D, E). A rubber band around the tubes prevents them from falling 
through the holes in the disc, and enables them to be lowered to any 
desired depth in the alcohol. 
The tissue to be dehydrated is packed closely in the dehydrating 
tube, and enough 50 per cent, alcohol poured over it to just cover it. It 
is then lowered through the hole in the disc until the two liquids are 
* New York Med. Record, 1890, pp. 177-9. 
t Amer. Mon. Micr. Journ., vii, (1891) pp. 7-8. 
