NOTES AND MEMORANDA. 
197 
aniline dyes, in tlieir solution in water, act like tlie acetate of potash, 
as they soften the film but do not loosen it from the glass. Amongst 
the aniline colours, methyl-violet and fuchsin appear to the author to 
work best ; he especially recommends the methyl-violet which is 
marked B B B B B in the price lists. When it is wanted to make the 
object more conspicuous for photographic plates aniline brown should 
be used. 
For preserving the preparations thus stained, either Canada 
balsam, a concentrated solution of potash, or glycerine may be used. 
Those preparations only which have been coloured in methyl-violet 
or fuchsin are adapted for placing in balsam. After being taken out 
of the staining liquid they are thoroughly dried and laid in the balsam 
in the usual way. Preparations coloured with methyl-violet and 
fuchsin, when they are to be photographed, must, in order to preserve 
the Bacteria in the most natural form, be placed, whilst still moist, 
in the solution of acetate of potash, and that must bo done directly 
after they are taken out of the staining solution, and they should 
then be sealed. Glycerine, as it takes out the colours, will not do to 
place these preparations in; on the other hand, it is the best pre- 
serving fluid for preparations coloured with aniline brown. 
As regards photographing, the Bacteria are not different from 
other microscopic objects. As, according to the process above de- 
scribed, the film to be photographed is immediately under the covering 
glass, the employment of the strongest immersion objectives is pos- 
sible. Under favourable conditions living Bacteria, which are not in 
a state of motion, may even be photographed, of which the author 
gives an example in a “ photogram.” He draws attention to the fact, 
that the photographic plate reproduces the microscopic image gene- 
rally better, that is more surely, than the impression on the retina of 
the eye can be. The article itself gives very explicit details of the 
process in photographing. 
As proof of the excellency of the productions obtained by his pro- 
cess the author gives three plates, containing twenty-four specially 
fine “ photograms ” ; on which the most delicate details, as, for 
instance, the flagella of the Bacteria, are plainly visible.* 
A Moisi Chamber of very simple construction for observing the copu- 
lation of the Spirogyra is described by Dr. Strassburger, in his book on 
‘ Fertilization and Cell Division.’ It consists of a ring of cardboard 
soaked in water, on which the covering glass is placed. The drop of 
water containing the Spirogyra must be suspended from the under 
surface of the covering glass, and may then be preserved for several 
days, and the copulation readily observed. If the plants are placed 
under the covering glass in the usual way, they will infallibly die. 
The “Zentmayer’* New Patent Microscope . — This instrument, 
which has just been introduced into this country by Messrs. Boss, 
resembles in aj^pcarance the well-known Jackson form of stand, but 
differs from it in the following particulars : — 
The limb supporting the body with the slide for quick adjustment, 
* ‘ Zcitbchrift f. Mikroakopio,’ vol. i. p. 119. 
