J28 Aaron Franklin Shiill 



In B, the parents came from the fourth generation of the well- 

 fed series in A above. In the preceding four generations five male- 

 producers had appeared among 172 female-producers. The best 

 food was used in each. 



In C, the parents were derived from a line that had been, for 

 four generations immediately preceding, fed from food cultures 

 that were past their optimum (see Experiment V); during this 

 time one male-producer and 185 female-producers had appeared. 

 The 16 next preceding generations were the first part of the starved 

 lineinExperimentlll. Food cultures that were past theiroptimum 

 were used in each line. 



The results of these three experiments are recorded in Table V. 



The three experiments point to the same conclusion as do those 

 parts of Experiment III which were performed at the same time, 

 namely, that feeding the rotifers a smaller quantity of food in- 

 creases the proportion of male-producers. This is the case no 

 matter whether the ancestors of the individuals experimented 

 upon had been starved (A), well-fed on fresh food (B), or 

 abundantly fed on old food (C), nor whether the preceding gen- 

 erations included few or many male-producers. It may be noted 

 also that the change in the well fed series in A, from a low to a 

 high percentage of male-producers, occurs almost simultaneousK 

 with a similar change in Experiment III. The two lines were onl\ 

 distantly related, but were fed on the same food. 



Influence of Age of Food Culture on Percentage of Male-producers 



Experiment V. On August 16, two sister individuals from thc- 

 sixteenth generation of the starved line in Experiment III were 

 isolated and became the parentsof two series of generations. Both 

 of thesewere fed abundantly, one from fresh food cultures, theother 

 from cultures that were deemed to be past their optimum. The 

 old food cultures, were on the average about ten days older than 

 the new cultures. The cultures in use at this time were made up of 

 about three liters of water, and required three to five days after 

 inoculation to reach their optimum. All that can be said with 

 certainty regarding the cultures used in the two lots is that one 



