Albuminous Substances and Saline Solutions. 123 



and in each case cut across the stem at the upper fiducial mark, and then, 

 using for the purpose pipettes drawn out into hair-fine stems, empty out 

 from pipette A and pipette B the contents of the capillary stem — com- 

 partment by compartment, planting out as we go upon nutrient agar. 



It will be found that in pipette B — that in which infected serum was 

 superimposed upon the salt — the microbes have been carried down to the 

 very bottom of the capillary stem. In pipette A — that in which an infected 

 watery fluid was superimposed — the microbes will have gravitated down only 

 a very short way. 



Experiment 2. — Two similar capillary pipettes, with stems divided off into 

 segments of equal length, are taken. A coloured mixture, consisting of 

 nine volumes of water mixed with one of staphylococcus culture, is intro- 

 duced by capillarity into the distal extremity of the one ; and a similar 

 quantity of a coloured mixture of nine volumes of serum and one of staphy- 

 lococcus culture into the other, the inflow being arrested when the fluid 

 reaches the first division mark. Then, in each case, the distal end of the 

 pipette is turned up sufficiently to displace the column of fluid, and to 

 bring it into position a little distally to the antepenultimate fiducial mark. 

 The tips of the tubes are now sealed up in a by-pass flame. Then, by means 

 of a capillary pipette drawn out into a hair-fine extremity, and carried down 

 into the stems of the pipettes A and B to a little short of the point where 

 the bacterial fluid is lodged, we — leaving here a bubble of air — fill in, in the 

 ease of the pipette B, a 3 per cent, solution of salt ; and, in the case of the 

 pipette A, water. 



The stems having been thus filled in, we take in each case a solid-ended 

 hair-fine glass thread (obtained by drawing out in the flame a piece of 

 capillary tube and fusing its end), and thrust it into the stem of the pipette, 

 carrying it down until it enters the bacterial fluid, and pushes this up level 

 with the penultimate fiducial mark. By the aid of the glass thread, the 

 fluid in the upper part of the stem is let down quite gently upon the 

 bacterial fluid — the intervening bubble of air mounting up the while to 

 find escape in the neck of the pipette. We now set aside the pipettes 

 for twenty-fours hours, and then emptying the compartments one by one 

 from above downwards, plant out the contents upon nutrient agar. 



The cultures so obtained show that, where salt solution is superposed upon 

 infected serum, the microbes are carried some distance up the stem ; while in 

 the case where we have water superposed upon microbes suspended in water, 

 they are confined to the distal end of the stem. 



It thus is manifest that we have in an hypertonic solution an agent which 

 is capable of drawing out from the cavities and ad-de-sacs of a wound and 



