The Process of Heredity 547 



in the solution they were all transferred to fresh sea-water and 

 allowed to recover in as far as possible. It was found that: 



H pures 5 alive and 5 dead, 50 per cent living. 

 H hybrids 6 alive and 4 dead, 60 per cent living. 

 M hybrids 8 dead and 2 living, 20 per cent living. 

 M pures none alive and 10 dead, o per cent living. 



The experiment shows no marked difference between the two 

 heteroclitus strains, but a more marked difference between the 

 two majalis strains. 



Experiment^. Fifteenof each of the four strains used. Embryos 

 seven days old. Same solution as in Experiment 3. 



After 2\ hours' exposure to the poison the embryos were trans- 

 ferred to fresh sea-w^ater and carefully washed. Sufficient time 

 was allowed for all not entirely dead to recover and then the dead 

 were counted: 



H pures 12 alive and 3 dead, 80 per cent alive. 

 H hybrids 6 alive and 9 dead, 40 per cent alive. 

 M hybrids i alive and 14 dead, 6 per cent alive. 

 M pures 4 alive and li dead, 26 per cent alive. 



This experiment shows the effect on the heteroclitus strains 

 to be about the same as before, but the conditions for the majalis 

 strains are reversed, the pure strain being the more resistant. 

 The hybrids had begun to show the enfeebling effects of a slower 

 circulation, which finally results in a failure of all specimens to 

 hatch. 



Experiment ^. This experiment dealt only with the two hetero- 

 clitus strains. Embryos nineteen days old. Same solutions as 

 before. The H hybrids showed the first effects of the poison, 

 four dying before any of the H pures. Three H pures survived 

 all of the H hybrids. 



The experiments with KCN show at least one thing, viz: that 

 the introduction of F. majalis sperm into the egg of F. heteroclitus 

 produces a hybrid with a lessened resistance to this particular 

 poison. 



