268 



A MANUAL OF BACTERIOLOGY 



aeroscope by substituting a flat-bottom flask for the 

 tube. 



Dr. P. F. Frankland 1 has devised a method by 



FIG. 54. COLONIES IN FLASK. 

 (After Frankland.) 



which a known volume of air is drawn, by means of 

 an air-pump, through a short glass tube (4 x i in.) 



1 Philosophical Transactions, vol. clxxviii. p. 113. 



