136 
Dll. P. P. PRANKLAND ON THE QUANTITATIVE ESTIMATION OF 
Colonies in flask. — (a) 65 
No. 2. Volume of air = 24 litres. 
Construction of 'plugs. — (a) Sugared glass-wool only. 
( b ) Sugared glass-wool and sugar-powder. 
Rate. — 2‘3 strokes per minute. (Tube exposed 32 minutes.) 
57 moulds. 
0 liq. 
( b ) 3 (all moulds). 
Control-tube, containing plug of sugared glass-wool and sugar-powder, 
exposed 78 minutes. 
'3 moulds. 
0 liq. 
This corresponds to 1 organism gaining access to plug in 16 minutes; 
2 colonies may, therefore, be subtracted from the colonies obtained both 
in No. 1 and No. 2 ; thus 
7 . . . fNo. 1, 25 colonies. 
10 litres of air yielded m \ _ T 
J J [No. 2, 28 
Colonies in flask, 5 
III. Laboratory window. October 5, 1886. Wind S. by S.W., fairly strong ; very 
variable in strength and direction. No recent rain. 3.26 p.m. to 5.11 p.m. 
23 c C. 
Comparison between glass-wool and sugared glass-wool plugs. 
Nos. 1 and 2 alternated in aspiration. 
No. 1. Volume of air =15 litres. 
Construction of plugs. — (a) Sugared glass-wool only. 
(b) Sugared glass-wool and sugar-powder. 
Rate. —-1‘3 strokes per minute. (Tube exposed 40 minutes.) 
~ 7 . . n - 7 . . f 50 moulds. 
Colonies in flasks. — (a) 58 j ^ ^ 
(b) 0. 
No. 2. Volume of air =15 litres. 
Construction of plugs. — (a) Glass-wool only. 
(6) Sugared glass-wool and sugar-powder. 
Rate. —1*2 strokes per minute. (Tube exposed 44 minutes.) 
Colonies in flasks.—(a) 55 j™ ou ^ s - 
. {h) °‘ 
Control-tube containing plug of sugared glass-wool only was exposed during 
50 minutes :— 
Colonies in flosk, 4 1° , m0ulds - 
lo liq. 
This corresponds to 1 organism gaining access to plug in 12*5 minutes; 
