132 



DAVID DAY WHITNEY 



TABLE 19 

 (From Shull and Ladoff) 



Showing the effect of oxygen and bouillon on one line, as contrasted with a line nol 

 subjected to either. Bouillon, even in dilute solutions, has been shown to reduce 

 the number of male-producers (see table 9). In this experiment, oxygen counter- 

 acts the effect of the bouillon, and actually increases the proportion of male- 

 producers above that in the control line 



1 40 per cent oxygen. Author. 



was oxygen apparently effective. Why was not the oxygen 

 effective in the other eight experiments? 



The experiments including the bacterial counts in table 8 gives 

 the answer to this question. It is seen by the bacterial counts 

 that it is impossible to make or to maintain two identical watch 

 glass cultures in which the rotifers are living. Under ordinary 

 air conditions two watch glass cultures may be made nearly 

 indentical and may remain nearly identical for twenty-four 

 hours, while another set of two watch glass cultures may be 

 practical identical when made but at the end of twenty-four 

 hours one of the two may contain only a few bacteria while the 

 other one may contain many more bacteria than at the beginning 

 of the twenty-four hour period. Furthermore, if two cultures are 

 made as nearly identical as possible at the beginning of the 



