338 HARRIET LESLIE WILCOX 



in the fourth. At the Research Laboratory, we have found 

 an abundant growth in 18 to 24 hours in the first generation 

 in glucose broth from the semi-soHd; this profuse growth con- 

 tinues in the subsequent cultures up to the third or fourth 

 generations, when there is a diminution, until in the sixth or 

 seventh, as frequently happened, no growth or very slight growth 

 appears after 48 hours or more. That is, out of thirteen cultures 

 transferred in the sixth generations, there may be only six or 

 seven tubes which show signs of growth, even after several 

 days incubation. 



At the Hygienic Laboratory, glucose stab cultures are used 

 for growing the stock strains, but it is not stated whether these 

 cultures are grown anaerobically or aerobically. The semi- 

 solid agar that we are using for the stock cultures is especially 

 satisfactory as no anaerobic conditions except such as the medium 

 provides are necessary to produce a heavy growth of B. tetani 

 with spore formation after a few days incubation. 



It is in the hope that other laboratory workers may find 

 the above technique of practical aid in producing an uniformly 

 potent toxin that these minute details have been given. 



