134 C. CLIFFORD DOBELL. 
Ordinary physiological salt solution usually makes the result- 
ing film too watery to fix ina proper manner, but I have found 
that salt solution containing about 15 per cent. of egg 
albumen answers admirably. The Bacteria from the large 
intestine of Amphibia live in this medium for a long time, 
and very good moist film preparations can be made. 
Swellengrebel uses a solution of gelatine for the same 
purpose, and has been successful with Bacteria and yeasts. 
The moist films made in this way should be as thin as 
possible and fixed immediately. For this purpose I know of 
nothing better than Schaudinn’s sublimate-alcohol (2: 1), 
used hot. Staining is best accomplished after this treatment 
by Heidenhain’s iron-hematoxylin. Very good permanent 
preparations can be made in this way. I do not find it 
necessary to wash out the sublimate with alcohol containing 
iodine, as is usually recommended. 
Good results may also be achieved by fixation with osmic 
vapour or in 1 per cent. osmic acid. And the method of 
fixation over the vapour from osmic and acetic acids (Plimmer, 
‘Proc. Roy. Soc.,’ B., Ixxix, 1907) gives good preparations. 
A very good and simple way of fixing is that used by 
Swellengrebel. A small drop of culture fluid is spread out 
on a coverslip with a small drop of formalin solution (I use 
Schering’s 40 per cent. formaldehyde) and allowed to dry. I 
find it best to harden the film in absolute alcohol for about 
fifteen minutes afterwards. One per cent. osmic acid can be 
used in the same manner as formalin. After such fixation 
Heidenhain or Giemsa may be used. Both give excellent 
results. Giemsa is not so successful after sublimate fixation. 
Although drying before fixing is not to be recommended, it 
sometimes gives quite good results when followed by alcohol 
fixation and Giemsa—the method used by Perrin for S piro- 
cheta balbianii. Fixation of moist films in absolute 
alcohol has often proved successful, but it not uncommonly 
causes plasmolysis. 
I have used the following method of staining with Giemsa 
without drying at any period in the process, and have found 
