450 V. A. POTTS. 



In the second table a fuller analysis of the experiments 

 lasting over the first six generations is given. An attempt 

 was made to isolate strains, constantly producing high 

 proportions of males, by breeding from a large number of 

 individuals of the same generation. Thus in the third genera- 

 tion a batch of 44 eggs produced 32 i and 12 <^ (5" (about 

 28 per cent.) did not, with one exception, maintain those 

 high proportions. One, however, though giving at first 

 hermaphrodites only, laid a batch of 16 eggs of which 11 

 became f and 5 ^ S (31 percent.). Nearly all these herma- 

 phrodites were kept for an examination of their progeny, })ut 

 five individuals, whose records were kept separate, furnished 

 strikingly retrogi-ade results, though males occurred in every 

 case but one. The male ratio was greater in a culture con- 

 sisting of the offspring of three individuals, renching 11 per 

 cent, of the whole number. Further selection for the next 

 generation proved equally indecisive. 



In the third generation a control series was also established 

 by taking sister individuals from a culture in which only 

 hermaphrodites were I'epresented. The total number of off- 

 spring of the five parents selected was 319, of which -302 were 

 i and 17 c^ c^ . This is exactly comparable to the total of 

 262 i and 15 ($ ^ produced by the five individuals from a 

 culture Avith 28 per cent, of males. The individual details 

 are closely similar in the two series. 



A brief inspection will serve to show how extraordinarily 

 irregular is the distribution of males in the progeny of any 

 single worm. There is no rule that they should appear at 

 stated intervals or restricting their production to a period or 

 periods of maturity, but on the contrary the appearance of a 

 few males from an early batch of eggs may be followed by 

 a succession of hermaphrodites only and vice-versa; the 

 last eggs may produce males when there have been only 

 hemaphrodites hitherto, or, again, males may occur in several 

 successive batches. 



