ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
689 
£. Technique.* 
Hints on Bacteriological Technique.! — Dr. Czaplewski gives a few 
practical hints on certain points often occurring in bacteriological work. 
Pipettes for obtaining samples of pus or other juices free from con- 
tamination with blood, faeces, &c., are often required. They may be 
made out of a piece of glass tubing a little longer than the ordinary 
test-tube, and from 3 to 4 mm. thick. One end is drawn out to a fine 
open point and then stopped with cotton-wool. The pipette wrapped 
round with cotton-wool is placed in a test-tube, and then dry or steam 
sterilised. 
Pieces of tissue should first be washed with water and then with 
1 : 1000 sublimate for about one minute, after which they are plunged 
in spirit for about half a minute. The alcohol is then burnt off so that 
superficial impurities are removed and the internal portions opened up 
by tearing or cutting for examination. 
Knives and syringes are freed from contamination by immersing them 
in caustic potash solution to soften the albuminous matters. These are 
then wiped off, the instrument dipped in spirit and the spirit burnt off. 
Gelatin should be boiled in a porcelain lined vessel, and this placed 
inside another saucepan filled with water, care being taken to prevent 
the gelatin pan from wobbling. 
Before inoculating birds their feathers should be wetted with spirit 
dabbed on with Cotton-wool. 
Infectious material and apparatus used in bacteriological work should 
be disinfected by boiling them for a good hour in a closed vessel, say a 
Papin’s digester, about half filled with water. This procedure is more 
trustworthy than the use of chemicals. 
Platinum loops should be of a definite size or sizes. These can be 
made by winding thin platinum wire round “standard” (1/2— 5 mm.) 
wires of definite thickness. In this way, not only is the loop circular, 
but holds a definite quantity. 
For inoculating eggs, the egg-borer used for blowing birds’ eggs is 
very convenient. To obtain samples of blood for bacteriological exami- 
nation, the skin should first be wiped over with strong caustic potash 
solution, and then washed with spirit. After this it is further disinfected 
with sublimate, followed by alcohol and ether ; after the evaporation of 
the latter the skin may be pricked. 
For imbedding small pieces for sectioning on a freezing microtome, 
cacao-butter is convenient as its setting point is 20°, while it is quite 
fluid at 37°. After removing the piece from alcohol it is placed in a 
mixture of cacao-butter and chloroform, which contains so much of the 
latter that it is fluid at room temperature. In this it remains for 1—24 
hours, according to the size of the piece ; it is then transferred to lique- 
fied cacao-butter (37°), and after a few to 24 hours sectioned. The 
cacao-butter is removed with turpentine, after which the sections are 
placed in alcohol. 
* This subdivision contains (1) Collecting Objects, including Culture Pro- 
cesses; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes; 
(4) Staining aud Iujecting ; ( 5 ) Mounting, including slides, preservative lluids, &c. ; 
(G) Miscellaneous. 
t Central!)], f. Bukteriol. u. Parasitenk., l te Abt., xx. (189G) pp. 307-13. 
