ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
727 
darkness ; while in the absence of air or in confined air the bacillus retains 
its power for long periods of time. 
Action of SeaWater on Microbes. * * * § — According to M. P. A. 
Cassedebat, sterilized sea water kills Staphylococcus aureus in 22-24 
days ; St. citreus in 19-22 days ; Friedlaender’s bacillus in 35-40 days ; 
anthrax in 21-24 days; bacilli of green diarrhoea in 16-20 days; 
Spirillum Deneke in 22-25 days; Proteus vulgaris in 23-26 days; 
typhoid bacillus in 48 hours. Cholera spirilla of various origin were 
still alive after 32-35 days, though in non-sterilized sea water they were 
defunct in a comparatively short time. 
Bacteriology of Teeth-pulp.j — Prof. Miller finds from an exami- 
nation of over 250 cases of diseased teeth, that affections of the pulp are 
usually the result of mixed infections, cocci and rodlets being present 
with fairly equal constancy, though long filaments and curved forms are 
not infrequent. The bacteria usually find their way to the pulp through 
the carious dentine, but a thin layer of hard dentine is insufficient to stop 
them. Suppurative conditions appear to be excited by cocci, though the 
typical pyogenic cocci, Str. pyogenes aureus and alhus and Str. pyogenes, are 
rarely to be found in pus from the pulp ; these cocci form a group of 
closely allied species, and have a marked pyogenic action on mice. The 
action of cocci on the pulp is much increased by decomposition ; this in 
its turn must be ascribed to the action of bacteria. 
Liquefaction of Gelatin by Streptococcus pyogenes.i — Dr. N. Pane 
states that Str. pyogenes will liquefy gelatin at temperatures over 28° 0. 
The nutrient medium is easy to prepare, but great accuracy is necessary. 
A 14 per cent, solution of gelatin is filtered through cotton previously 
boiled in a soda solution. It is then steam-sterilized for 5-6 minutes, 
and afterwards cooled down with water. In making this nutrient gelatin 
which liquefies at 30°, it should be borne in mind that the melting point 
of the gelatin falls inversely to the time during which the temperature 
has acted. This property of liquefying gelatin under the conditions laid 
down by the author may be regarded as a specific characteristic of Str. 
pyogenes. 
Immunity to Diphtheria.§ — From a series of experiments relative 
to artificial immunity and diphtheria, Dr. J. Kuprianow concludes that 
the blood-serum of rats naturally immune to diphtheria is unable to 
protect other animals against this disease. But by treating rats with 
virulent living diphtheria cultures, an immunizing power is imparted to 
their blood-serum, and this result is attained by injecting separately 
small doses, or larger ones at greater intervals, of diphtheria bouillon 
cultures (0’1 ccm. per diem, 1 com. per week, and up to 5 ccm. 
eventually). By the aid of the blood-serum of immunized rats, and 
subsequently (3-4 weeks) by injections of diphtheria bouillon cultures, 
guinea-pigs can be rendered immune in about three months ; and with 
* Rev. d’Hyg. et de Pol. San., 1894, p. 101. See Centralbl. f. Bakteriol. u. 
Parasitenk., xvi. (1894) p. 265. 
j Verhandl. Deutsch. Odontol. Gesellsch., vi., Nos. 1 and 2. See Centralbl. f. 
Bakteriol. u. Parasitenk., xvi. (1894) pp. 447-55 (27 figs.). 
i Centralbl. f. Bakteriol. u. Parasitenk., xvi. (1894) pp. 228-30. 
§ Tom. cit., pp. 415-34. 
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