I38 REPORTS ON INVESTIGATIONS AND PROJECTS. 



depth from which a sample was desired. Recent work on the bactericidal 

 effects of metals suggested that it was undesirable to employ a water-bottle 

 the receiver of which was made of metal, and some test experiments were 

 made which conclusively showed that for the collection of samples of sea- 

 water neither copper, brass, aluminum, bronze, silver, nor nickel were suita- 

 ble metals, and indeed that a very large proportion of the bacteria were 

 killed by exposure to the action of these metals for an hour or more. The 

 use of exhausted glass bulbs presents considerable difficulties for depths 

 as great as 800 fathoms. The bulbs must be strong and very thoroughly 

 annealed, as otherwise the slight shock caused by breaking off the capillary 

 neck is liable, under the great pressure, to make the bulb fly into small frag- 

 ments. Another great disadvantage is the strong probability that the sudden 

 reduction in pressure to which the water is exposed as it enters the bulb 

 would immediately kill any bacteria in the water. 



In order to overcome the difficulties presented by the use of either of 

 these types of apparatus, a water-bottle on a new principle was designed for 

 me by Mr. D. J. Matthews, hydrographer to the Marine Biological Associa- 

 tion of the United Kingdom and to the Irish Fisheries Board. The con- 

 tainer of the bottle consisted of a strong glass cylinder, with ground ends, 

 holding about 250 c. c. This was closed at each end by rubber washers 

 through the center of which a short piece of thin-walled rubber tubing 

 passed, the tubing being sealed at the end within the cylinder. An appa- 

 ratus was arranged with which, by sending down two messengers, the 

 cylinder could first be opened and then closed at both ends at any required 

 depth in the sea. The whole apparatus was first sterilized by steaming in a 

 "Koch," and then the cylinder was completely filled with 95 per cent alcohol. 

 The washers were kept tight on the ends of the cylinder by strong springs, 

 so that no leakage occurred. 



When the cylinder was opened by sending down the first messenger, the 

 alcohol, being of lower specific gravity than sea-water, diffused out almost 

 instantaneously, causing an upward current of water to flow through the 

 cylinder, which was then closed by the second messenger and hauled to 

 the surface with its contained sample of water. The washers with their 

 attached pieces of thin rubber tubing had sufficient capability of bulging 

 inwards to allow for contraction of the alcohol due to the low temperature 

 at any considerable depth, and to its compressibility being greater than that 

 of sea-water ; and similarly the expansion of the sample of water as the ap- 

 paratus was hauled up was compensated for by the partial collapsing of the 

 thin-walled rubber tubing. 



It is obvious that even had a slight amount of leakage occurred, a leakage 

 inwards during the descent of the apparatus would not vitiate the results, 

 as bacteria would promptly be killed in the 95 per cent alcohol ; similarly, on 

 hauling up, the leakage, if any, would be outwards, due to the expansion of 

 the sample through the regularly increasing temperature, and so the sample 

 would not be contaminated by any of the surface layers through which it 

 was hauled. There was, however, no reason to suppose that any leakage 

 occurred. 



After the first sterilization by steaming, the action of the alcohol was 

 relied on for sterilization between successive samples, and both experiment- 

 ally and in practice this method was found to be absolutely safe, as all the 

 marine bacteria are very readily killed by the action of alcohol and they do 

 not form resistant spores. After the collection of a sample it was siphoned 

 off into a sterilized glass bottle by means of a sterilized length of rubber 

 tubing. 



