132 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
taining whether the proportion of alkali advocated by Maassen and used 
in the Imperial Laboratory at Berlin is the correct one, viz. 1*035 ccm, 
per cent, normal soda solution to 1 litre litmus-blue neutral bouillon, and 
also whether the addition of caustic soda or of soda is more advantage- 
ous for bacterial growth. Twenty different species of bacteria were 
used for the research. The conclusions the author arrived at were : — 
(1) The addition of soda for the great majority of the bacteria 
examined was found to be more advantageous than caustic soda. In a 
small number of bacteria there was no difference between the two. 
With diphtheria the growth was usually better with caustic soda than with 
soda. With anthrax the growth was invariably better with caustic soda. 
(2) A slight addition of alkali beyond the litmus-blue neutral point 
was advantageous for most bacteria, only B. pyocyaneus and B. cyano- 
genus thriving better on neutral media. 
(3) The optimum lay between 0*34-1*7 ccm. per cent, normal 
caustic soda solution, and 0 * 39-1 * 95 ccm. per cent, normal soda solution. 
The addition of 1*15 per cent, of crystallised soda over the litmus-blue 
neutral point, corresponding to 1*05 ccm. per cent, normal caustic soda 
solution, as used by Maassen, seems therefore suitable for most bacteria. 
(4) The limits for good growth lay generally between 1*7-3 *4 ccm. 
per cent, normal caustic soda solution and 1*95-3*9 per cent, normal 
soda solution. With diphtheria, however, the limits reached were only 
1*0 ccm. per cent, and 1*17 ccm. per cent.; while with B. ruber 
Plymouth , B. erythrogenes, V. Miller they were 5 * 1 ccm. per cent, and 
5*85 ccm. per cent, respectively. 
(2) Preparing- Objects. 
Apparatus for Filtering Bacterial and other Fluids.* — Dr. F. G. 
Novy describes a filtering apparatus, the principal advantage of which is 
that the positive pressure from the compressed air co-operates with the 
negative pressure of a pump in filtering the fluid, so that in 3-5 minutes 
250 c.cm. of water can be passed through. 
The essential parts of the apparatus are a glass cylinder, and a 
Chamberland bougie, which is inserted within the cylinder. The latter 
has a flange at the lower end, by means of which, through the intermedi- 
ation of clamps and caoutchouc rings, it is firmly fixed to the bougie. 
Simple Steam Steriliser.^ — Dr. F. G. Novy recommends a simple 
apparatus for steam sterilising. The lower part is the ordinary Hoff- 
mann’s iron water-batli, 18-20 cm. in diameter. The upper part, made 
of copper, has a perforated bottom. Inside are soldered two rings 
1J cm. broad, of perforated copper, one about 4 cm., the other about 
12 cm. from the bottom. The object of these rings is to prevent the 
culture tubes from touching the sides. The lid is furnished with a tube 
for the escape of the steam. 
(4) Staining: and Injecting:. 
Staining Yeast-Cells.J — Herr O. Busse, in his work on }*easts as 
causes of disease, recommends the following method for staining these 
* Centralbl. Bakt. u. Par., l te Abt., xxii. (1897) pp. 337-9 (2 figs.). 
t 'Pom. cit., p. 340 (1 fig.). 
+ ‘Die Hefen als Krankheitserreger,’ Berlin, 1897. See Centralbl. Bakt. u. Par., 
1‘ 8 Abt., xxii. (1897) p. 349. 
