345 
barren. It was then treated with boiled solution of pure 
sugar. As on March 21 the liquid was still entirely free 
from organic forms it was sown with some fresh spores of 
penicillium. Up to the present time there has been no 
change. 
XX.—February 23.—For the purpose of investigating the 
zymotic property of any water, it may be conveniently col- 
lected in a tube of the form and size shown in Fig. 1. 
It is essential that it should be used in a state of absolute 
purity. As it is seldom possible to draw the tube at the 
time that it is to be filled, it must, as a rule, be prepared 
beforehand, in which case it is necessary to close it hermeti- 
cally at both ends before it is removed from the flame. Such 
a tube obviously contains calcined air, of which the tension 
is very much less than that of the atmosphere ; consequently 
it is very easily filled by breaking off its end under the sur- 
face of the water of which a specimen is to be collected. If 
the water is flowing from a tap or in a stream it must be 
received in a boiled capsule, in the contents of which the 
tube may be dipped. 
Fifteen specimens of water supplied by the London com- 
panies were collected in this way during February last, and 
tested with reference to their zymotic power on the 23rd of 
the same month. The results of the experiment are exhibited 
in the following table, in which the number printed below 
the designation of each specimen indicates the order in which 
it would have stood if the tubes had been arranged in a linear 
series according to the degree of turbidity which each mani- 
fested on the ninth day after impregnation. 
Letter designating Aiton eae cal Water after filtration| Water as distributed 
Water Company. | cidence reservoir). (from pump well). (from main). 
A 15 3 13 
B 14 10 7 
C 5 2 6 
D I 12 8 
E 4 9 ll 
The specimens to which the numbers 15, 14, 13, 8, 7, 5, 
correspond, became hazy as early as the fifth day. On the 
ninth day it is noted that the eprouvettes to which the six 
highest numbers correspond were milky, while those in which 
the turbidity was least marked were merely hazy; the rest 
