INDUCED CHARACTERS IN ASPLANCHNA AMPHORA 369 



rienced in obtaining resting eggs from the saccate type. However, 

 a mass culture started on January 29, from the fifty-third genera- 

 tion of / and remaining purely saccate, produced by February 6 

 resting eggs. These began to hatch by February 12. Unfor- 

 tunately, at this time the labor of caring for the enormous pro- 

 geny of the ten lines oi J 2, as well as of the original series, ren- 

 dered it impossible to establish more than a single additional 

 series. This, started from one of the before-mentioned resting 

 eggs drawn from the saccate series, /, we term series / 2. It thus 

 forms a parallel or contrast series to the ten lines in J 2. Other 

 individuals derived from sister eggs, as well as from other resting 

 eggs produced at the same time in the same culture, were set aside 

 to form mass cultures useful in a general way as checks or con- 

 trols. The history of J ^ as well as of the contrasted series / 2 

 are given in table 2. 



It will be seen from table 2 that seven of the series in J 2 were 

 bred for ten generations, the other three succumbing to total male 

 production after six to eight generations. / 2 was bred to thirty 

 generations. 



It will be noted that again sexual reproduction fails to wipe out 

 the induced but hereditary tendencies of the contrasted series. 

 Although conditions were in every way parallel the transition from 

 the saccate to the humped type occurred early in each of the ten 

 lines of / 2, while in 7 ^ no transition whatever occurred. In 

 reality the contrast is even stronger than indicated by this general 

 statement, for not only is there no tendency toward mutation 

 displayed during the entire thirty generations oi I 2, but in not 

 one of the above mentioned mass cultures derived from the resting 

 eggs of the same source did the humped type appear. The 

 exact generation, on the other hand, in which the humped type 

 appeared in the lines oi J 2 were, respectively, the ninth, fifth 

 second, third, third, third, fourth, sixth, fourth and third. It is 

 noteworthy that even in the one instance where the transition in 

 the direct line was delayed till the ninth generation sister indi- 

 viduals to the one in the direct line made the transition as early 

 as the third generation. 



