Testing Germicidal Value of Liquids 267 



each transfer takes an average of fifteen seconds, the operator must 

 have every detail of the technic so well in hand, and the materials 

 so conveniently placed, etc., that he can complete the entire per- 

 formance of the technic from the addition of the culture to the 

 seeding tubes to the last transplantation from seeding tubes to 

 subculture tube without a hesitation and without a distraction. It 

 is on account of the necessity of this "continuous performance" 

 that such care was taken to point out the exact details of 

 apparatus and materials needed, before describing the technic. 



To return to the seeding of the tubes, a sterile pipet graduated 

 in Ho cc. is used. The cotton stoppers are removed from the 

 seeding tubes and thrown away as of no further use. One by 

 one as the time arrives, tubes are taken in one hand, inclined to 

 an angle of about 45 degrees, while the tips of the pipet are lightly 

 touched to that side of the tube from which the fluid has run away 

 on account of the slanting, and exactly o.i cc. of the culture de- 

 Uvered. This may under no circumstances take longer to perform 

 than fifteen seconds, and if one succeed in finishing it in a shorter 

 time, he must wait until the calculated time arrives before dehvering 

 the culture into the next tube and so on until the end is reached. 

 Each tube is given three gentle shakes after being straightened up, 

 then returned to the water-bath; 



With a ten-tube series, and a time allowance of fifteen seconds 

 for each tube, the entire series of tubes is no sooner completed 

 than the time (two and one-half minutes) for making the first 

 series of transplantations to the subculture tubes has arrived. 

 The operator therefore seizes at once the first of the culture tubes 

 in the two and one-half-minute series with one hand, and a sterile 

 platinum loop with the other. He cautiously removes the cotton 

 plug from the culture tube, and at the proper moment intro- 

 ' duces the platinum loop into the first seeding tube all the way 

 to its bottom, withdraws it, and carries one drop of the con- 

 tained fluid into the first subculture tube which he plugs and places 

 in the empty hole to the left of the row in the block, at once taking 

 up its neighbor on the right. As only fifteen seconds are allowed 

 for each such transfer, the operator must proceed without hesitation. 



There is no time to sterilize the platinum loop, so he lays it on 

 the block, pushes the flame under it and takes up an already steril- 

 ized loop with "which he performs the same act of transplantation 

 for the second tube that was done for the first, doing it on the 

 appropriate second of time, and so continuing through the whole 

 series. 



Every test of the phenol coefficient of disinfection must em- 

 brace two such series, one made with the dilutions of the phenol 

 that is to act as the standard, the other made with the dilutions of 

 the disinfectant to be determined. If, however, a variety of dif- 

 ferent germicides are to be tested the same day, one phenol test 



