ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
555 
The material containing the bacteria is to be diluted with bouillon 
until 2-3 ccm. of the fluid contains less than 1000 viable germs if each 
depression is to contain representatives of one species only. Excess of 
fluid should be removed from the surface with strips of stiff, smooth, 
sterilized paper. The plates are then incubated at any temperature and 
in a few days characteristic changes may be observed in the bouillon. 
If the fluid inoculated has been sufficiently diluted the number of pure 
cultivations will predominate. Special care is to be taken that the 
droplets do not run together. 
Dr. K. Holten * states that he has used a similar method of cultivation 
for some time. A number of separate compartments are made in a glass 
plate by means of asphalt or the like substance. Each square space 
receives, by means of a fine pipette, a droplet of fluid ; the fluid fills but 
does not exceed the whole space. To prevent contamination each plate 
should be covered with another, the two being about 2 mm. apart and 
separated by means of strips of asbestos fixed with some adhesive or by 
plaster of Paris. 
The author uses plates 12 by 9 cm. divided into seventy compartments 
and finds that the larger the plate the better the result ; the breadth, 
however, should not be too great to prevent every part from being ex- 
amined under the Microscope. The plates may be dry or steam 
sterilized. 
The material to be examined should be so diluted with the nutrient 
solution that not more than 1/4 of the drops are infected, and if the ap- 
proximate number of germs in a definite quantity be unknown then 
plates of different dilutions must be made. If, however, it be important 
that the composition of the nutrient fluid should not be altered, then the 
nutrient medium must be correspondingly concentrated. The plates 
should be incubated in a moist chamber in order to compensate for 
evaporation. For a day or two the infected drops begin to get cloudy, 
and then they may be examined macroscopically and microscoiiically. 
Action of Disinfectants on dry and wet germs.t — MM. Ch. Cliam- 
berland and E. Fernbach give the results of numerous experiments with 
eau de Javelle, chloride of lime, peroxide of hydrogen, and sublimate 
on Bacillus subtilis. This particular organism was selected on account 
of its great resisting power, and the action of the disinfectants was tested 
against the germs in the moist and dry condition. In the moist condition 
a definite quantity of a liquid culture was mixed with a definite quantity 
of the disinfectant, and the two well shaken up together. From the 
mixture cultivations were made at various intervals, some of the undis- 
infected cultivation being kept for control. The experiments on the 
germs in the dry condition were made in the usual manner, that is to 
say, they were dried on pieces of glass or silk threads. The authors con- 
clude from their experiments that commercial eau de Javelle (hypo- 
chlorite of soda), chloride of lime (a solution of 100 grm. in 1200 
grin, of water, diluted with ten times the volume of water), commer- 
cial oxygenated water (H 2 0 2 ) are more active than an acid solution of 
sublimate (1-1000). These disinfectants do not, or only after several 
* Centralbl. f. Bakteriol. u. Parasitenk., xiii. (1893) p. 753. 
f Ann. Inst. Pasteur, vii. (1893) pp. 433-80. 
2 Q 
1893. 
