28 Canadian Record of Science. 
additional bacteria from the air. Both of these objects 
ure met by the flattened glass flasks designed by Petruschky. 
These flasks contain the nutrient gelatine ready for use, 
so that it is only necessary to warm them gently and so 
melt the gelatine, drop in the proper amount of water and 
after shaking them gently to lay them on their side till the 
gelatine stiffens. 
As these flasks are expensive and not always easy to ob- 
tain, it may be of interest to those who work under condi- 
tions which make it difficult to obtain apparatus to know 
that I have found ordinary fiat sided, common, white glass 
vials, obtainable anywhere, answered the purpose admir- 
ably. Owing to the small size of the bottle necks I find it 
best to plug them by wrapping the cotton wool about 
the end of a wooden toothpick, which is then broken off 
short. By doing this the plug can be readily inserted and 
removed. The colonies are readily counted with a lens, 
and to facilitate this I rule with a writing diamond a couple 
of parallel s:ratches on the flat side of the bottle in the 
axis. Cross lines are not usually necessary. Any of the 
colonies can be fished out with as much ease as from a 
Petruschky flask. The only respect in which these bottles 
are not satisfactory is that, being made of rather thick 
glass, when using a low power microscope, the object ap- 
pears somewhat blurred. This also could probably be 
obviated by using a correcting lens. They possess, how- 
ever, a distinct advantage over the Petruschky flasks in 
being much stronger. They also pack closer, owing to 
their flat sides, and having flattened bottoms they can be 
stood up. 
For summer field work I was able to pack 160 of the 
bottles in a small double walled tin chest or portable 
refrigerator, measuring 20” x 16x18”, and this included 
a space of 8” x 8’’ x 18” for the ice chamber. 
