544 H. H. N 



ewman 



most immediate effect of the carbon dioxide, the heart-beat of all 

 five specimens ceasing before the expiration of 5 minutes. The 

 M pures lasted, on the average 7 minutes. The H pures averaged 

 18 minutes. The H hybrids averaged nearly 30 minutes, all 

 continuing* to live after all of the other embryos were dead. 



Experiment 2, June 26, igoj. Six embryos of each strain, 

 eight days old. The M hybrids all stopped before any of the 

 others. The M pures began to show the effect of the carbon 

 dioxide a little later than the M hybrids and survived considerably 

 longer. The H pures stopped a few minutes later, while four out 

 of six a hybrids continued nearly twice as long as the H. pures. 



Experiment J, July 8, igoj. Ten embryos of each strain used. 

 All 4 days old. 



After 5 minutes, 6 M hybrids and 5 M pures dead. 

 After 10 miniates, 7 M hybrids and 5 M pures dead. 

 After 19 minutes, 8 M pures dead, one feeble and one 



active. 

 After 21 minutes, 7 M hybrids dead, 3 very feeble. 

 After 28 minutes, all M pures and M hybrids dead. 

 After 33 minutes, 4 H pures dead, no H hybrids dead. 

 After 38 minutes, 6 H pures and 2 H hybrids dead. 

 After 45 minutes, 7 H pures dead, 2 feeble, i fairly strong; 



4 H. hybrids dead, the rest strong. 

 After 50 minutes, 9 i/ pures dead, i feeble; 4 H hybrids 



dead, i feeble, 5 strong. 

 After 60 minutes, all H pures dead; 5 H. hybrids dead, i 



feeble, 4 strong. 

 After 75 minutes, 8 H hybrids dead, 2 strong. 

 After 85 minutes, all H hybrids dead. 



The experiment shows that, in embryos of four days, there was 

 practically no difference between the two majalis strains, but that 

 the H hybrids were considerably more resistant than the //pures. 



Experiment ^, July p, igoj. An attempt was made to select 

 embryos of the same degree of advancement instead of the same 

 age. The embryos were selected from different series and were 



