488 G. H. DKEW. 



between successive samples, and both experimentally and in practice 

 this method was found to be absolutely safe, as all the marine bacteria 

 are very readily killed by 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: this 

 method was considered preferable to any arrangement of taps leading 

 from the collecting cylinder, owing to the difhculties of cleaning and 

 sterilization which would be involved. Part of the sample was 

 also siphoned off into bottles, which were returned to Plymouth for 

 analysis for salinity: these bottles had previously been thoroughly 

 washed and rinsed with several changes of distilled water, and then 

 dried in an oven ; they were closed with rubber stoppers. 



It was found in practice that this design of water-bottle worked 

 extremely well and gave very little trouble ; it is to be noted that the 

 sample of water collected is kept only in contact with rubber and glass 

 throughout, so that the bactericidal action of metal is avoided. 



Surface samples of water were taken in wide-mouthed stoppered 

 bottles, holding about twelve ounces ; the samples were always taken 

 from the bows of the boat when moving ahead, in order to avoid any 

 possible contamination from the sides of the boat. 



Some samples from depths up to 80 fathoms were collected off the 

 Tortugas in 1911 in retort-shaped glass flasks of about 300 c.c. capacity, 

 with narrow, recurved, long-drawn-out necks. These were sterilized, 

 exhausted, and sealed ; they were then lowered in an apparatus in 

 which the extremity of the neck could be broken off at any desired 

 depth by sending a messenger down the sounding wire, when the 

 flasks became completely filled with water. After hauling up, a little 

 water was shaken from the neck, and it was then sealed with the 

 blowpipe. By this method risk of contamination from more super- 

 ficial layers of water as the apparatus is drawn up is avoided, since 

 the changes in pressure and temperature as it ascends tend to cause 

 a continuous outflow through the narrow neck until the surface is 

 reached. 



A somewhat similar apparatus was used for obtaining deep samples 

 from the station 70 miles west of Ushant, but the glass bulbs were 

 smaller, and the tube leading from them was bent at right angles to itself. 

 Considerable difficulty was caused by the breaking of the tube owing 

 to the force of the inrushing stream of water impinging on the wall 

 where it was bent at right angles. 



If this form of apparatus is vised, all sharp angles in the inlet tube 

 should be avoided, and it should be so arranged that the inrushing 



