134 
DR. P. P. FRANKLAND ON THE QUANTITATIVE ESTIMATION OF 
Rate. —5 strokes per minute. (Tube was exposed 18 minutes.) 
~ 7 . • n i -.r. f 67 moulds. 
Colonies m flask, 139 j ^ ^ 
No. 2. Volume of air — 24 litres. 
Construction of plug. —Glass-wool only. 
Rate.—6'6 strokes per minute. (Tube exposed 12 minutes.) 
„ 7 . . „ 7 „ „ , f 68 moulds. 
Colonies m flask, 1641 
J 10 liq. 
Control-tube to Nos. 1 and 2 contained plug of sugared glass-wool only; it 
was exposed 57 minutes, but, as the flask contained only one colony, 
nothing need be subtracted from the results of Nos. 1 and 2, as they 
were only exposed 1 8 and 12 minutes respectively. 
Nos. 3 and 4 were alternated in aspiration 3.34 p.m to 4.7 p.m. 
No. 3. Volume of air = ] 8 litres. 
Construction of plug. —Sugared glass-wool only. 
Rate. —4'3 strokes per minute. (Tube exposed 14 minutes.) 
~ 7 . . „ 7 f 7 2 moulds. 
Colonies m nask, 1141 
J [O liq. 
No. 4. Volume of air =18 litres. 
Construction of plug. —Glass-wool only. 
Rate.- —6‘6 strokes per minute. (Tube exposed 1T5 minutes.) 
59 moulds. 
2 liq. 
Control-tube for Nos. 3 and 4 with sugared glass-wool plug gave colonies in 
flask 0. 
f No. 1, 58 colonies. 
No. 2, 68 
No. 3, 63 ,, 
[No. 4, 65 
Colonies in flask , 117 
10 litres of air yielded, therefore, in <{ 
The above experiments tend to show that the plugs employed arrested the whole 
of the organisms, since in comparative experiments the more impervious plugs did not 
yield a larger number of colonies on cultivation than the more pervious ones. It was, 
however, deemed advisable in further experiments to have in each case a guarantee 
that all organisms were stopped, and for this purpose the doubly-plugged tubes, 
which have been already described, were constructed and invariably used in my later 
experiments. 
