200 MEDICAL BACTERIOLOGY 



From the above it will be seen that each seeding tube, as the test is con- 

 ducted, contains 4 cc. of the disinfectant dilution plus i cc. of organic matter, 

 plus o.i cc. of typhoid culture, and that the quantity of organic matter repre- 

 sented is 3 per cent. 



In computing the strengths of the disinfectant and the percentage of organic 

 matter present in the seeding tubes when the test is made, we have disregarded 

 the slight change resulting from the addition of the o.i cc. of typhoid culture 

 to each tube. By so doing the experiment is very much simplified, as it would be 

 very difficult to prepare the dilutions of the disinfectant on the basis of allowing 

 for so slight a change as is caused by the addition of o.i cc. of liquid. 



