476 DOROTHY F. PETTIBONE, F. B. BOGART AND P. F. CLARK 



TABLE 3 

 Column 2 cm. high Suspension of B. 

 prodigiosus introduced as in table 1 



TABLE 4 

 Column 3 cm. high. Suspension of B. 

 prodigiosus introduced as in table 1 



These tables show that the efficiency of a bubble fountain de- 

 pends partly upon the height of the jet thrown. But even at the 

 maximum height used, 4 inches, which is higher than practicable, 

 some organisms are still retained in the column for about 2 

 minutes. Considering also the fact that when the organisms 

 were introduced on the moist lips, a very small number were 

 added as compared with the milUons introduced in the turbid 

 suspension by means of the pipette, it is possible that the saliva 

 of the mouth may be a factor in causing the bacteria to remain a 

 longer time than would otherwise be the case. 



How shall we explain these facts and how shall the bubble 

 fountain be made safe for public use? 



Our conception of the problem is that the organisms dance in 

 the column of water much as the toy ball dances on top of the 

 fountain in the garden. Most of the organisms introduced are 



