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MRS. G. C. FRANKLAND AND DR. P. F. FRANKLAND 
the relative facility with which the organism has by experience been found to take 
the colouring matter ; it is then washed off with distilled water, and, if intended for 
immediate examination, laid with the film-surface- downwards upon a clean glass slip. 
The excess of water is then carefully removed with blotting-paper, and the prepara¬ 
tion is ready for examination. If the preparation is intended for permanent preserva¬ 
tion, it is, after washing off the dye, allowed to dry, and then mounted with a drop 
of Canada balsam. 
Drop-cultivations .—We have also studied the motility and progressive growth of 
the various organisms in “ drop-cultivations.” The drop-cultivations are prepared as 
follows :— 
A cover-glass is sterilised by holding it with a pair of forceps and passing it several 
times through a Bunsen-flame or spirit-lamp. A glass slip having a round excavation 
on one surface, and capable of being completely covered by the cover-glass, is similarly 
sterilised, and both cover-glass and slip are allowed to cool under a glass shade. 
When cool, a small drop of sterile broth is placed by means of a sterile looped platinum 
needle in the centre of one surface of the cover-glass, and immediately after a very 
minute quantity (the smaller, the better) of a cultivation of the organism under 
examination is introduced by means of a sterile platinum needle into the drop of 
broth, and the cover-glass bearing the latter is then carefully placed so that the 
drop upon its under-surface projects into the centre of the excavation. The periphery 
of the excavation has been previously coated with a thin layer of vaseline, so that 
when the cover-glass is placed in position as described the vaseline produces an 
air-tight seal to the small circular cell which is thus formed. 
If the above manipulations are performed with due care, a perfectly pure cultivation 
is obtained, and its progress can be observed under the highest powers of the 
microscope. 
By the aid of the above-described methods we have endeavoured to accurately 
characterise a number of micro-organisms which we have obtained from air. A few of 
these, such as the Micrococcus prodigiosus, the Bacillus subtilis, the yellow and orange 
Sarcinci, have been more or less closely described by other observers, but the remainder 
are entirely new, or, if previously observed, they have not to our knowledge, after 
careful reference to the most recent literature, been so described as to render them 
capable of identification. Under these circumstances we have felt it necessary to 
provisionally give names to all those forms which have not been hitherto described. 
The names which we have selected for this purpose are generally of such a nature as 
to indicate some striking peculiarity which the organisms present either in their 
cultivations or when viewed under the microscope. By adopting this plan, we believe 
that the description of, and reference to, the organisms which we have had under 
observation will be facilitated more than if we had only designated them by numbers 
or other symbols. 
