99 Canadian Record of Science. 
this the precautions necessary to guard against contamina- 
tion of the wire while attaching the string, and the neces- 
sity of having a separate bottle for each sample collected, 
rendered them inconvenient for field use. 
The method of using sealed tubes or flasks with a — 
tapering end bent at right angles to be broken off under the 
water, has been recommended by Escherisch of Munich. 
This is much more free from technical sources of error 
than the apparatus last mentioned, but the trouble of pre- 
paring such flasks is considerable, as one has to be manu- 
factured for every sample to be taken. 
In the last edition of Rohrbeck’s catalogue I find an ap- 
paratus figured for collecting bacteriological samples at 
different depths. From the impression conveyed by the 
illustration it seems too complicated to be easily handled, 
and the entire apparatus evidently requires to be re-sterilized 
before a second sample can be taken. 
At this stage my attention was directed to a most ingenious 
apparatus invented by Prof. Ellis of Toronto University, 
which differed from all the others in principle. This was a 
device by which sterile glass stoppered bottles could be 
placed in a weighted frame and lowered to the required 
depth. By pulling a string the stopper could then be raised 
sufficiently to allow the water to enter. By releasing this 
end the stopper was instantly replaced by means of a spring. 
Any number of samples could be taken, as the bottles could 
be placed in the frame one after another with very little 
loss of time. The advantages of this as compared with 
the plans described above are very great. There is 
absolute certainty that no water is obtained from any 
except the required depth. There is no limit to the number 
of samples which can be taken, and all the preparation 
necessary is limited to sterilizing the bottles. It is also far 
more economical, as a single sinking frame contains in itself 
the attachments for opening and closing the bottles. 
The instrument I am about to describe is a modification 
of that devised by Prof. Ellis, and I ean claim no origin- 
ality whatever with regard to the principle of opening 
