212 
Ward. —Thames Bacteria , II L 
Just before 9 p.m. the softening gelatine gave way and 
the sphere began spreading itself out as a film, but I was 
unable to do more than satisfy myself that the rods and 
filaments themselves move. 
Repeated attempts to bring the colony in the hanging- 
drop to the creeping stage observed in such perfection on 
the plates failed in some cases, evidently because the small 
drop of gelatine becomes exhausted before the colony is 
ready to spread, in other cases because the drop got diluted 
and too thick for focussing even with the E/4. 
Eventually I abandoned this method in favour of another, 
the extraordinary success of which suggests its wider applica- 
tion in such researches as these. 
I took a clean cover-slip, and sterilized it by holding it 
over the flame between talc plates, and spread a thin film of 
sterile gelatine on it and allowed it to set. I then lifted 
it by sterile forceps so arranged that one point held the 
middle of one edge and the other point the middle of the 
opposite edge ; hence the cover-slip was so jammed between 
the forceps that when the latter were held vertical, the former 
was horizontal ; and I then brought the sterile cover-slip, 
gelatine-side down, on to one of the creeping films on a two 
'lays’ plate-culture. In fact, I made a ‘ Klatsch-praparat * of 
the creeping film, and after a few attempts obtained a very 
perfect specimen. The cover-slip was then fixed as the roof 
of one of my sterile culture-cells, and treated exactly as in 
the case of a hanging-drop. 
After a few minutes at 20° C., I then saw under the 
immersion one of the most magnificent sights in the way of 
bacterial movements it has ever been my lot to witness. 
The lobes and flame-like protuberances of the coronal film, 
as well as some of the looser bacterial aggregates from the 
centre of the colony, had been taken up and fixed by the 
gelatine to which they adhered in their relative positions : 
the impress of the film was particularly perfect, and after 
recovering from the shock, the movements of the lobes and 
wandering outliers went on in the now swelling film of 
