Effects of Oxygen on Dove Embryos. 



103 



pressures. The earliest stages, in fact, wholly lack the usual or 

 other apparent mechanisms of respiratory compensation. Con- 

 trary to permissible inferences from the few studies hitherto made 

 with older embryos only, it is found that the embryos in the 

 youngest stage are usually much affected by prolonged high con- 

 centrations of oxygen. Some of these embryos are killed by 

 subjection to high oxygen pressures during 24 hours; others may 

 temporarily survive — as shown by heart-beat — for more than four 

 days, but these embryos usually fail to develop blood pigment, 

 become highly abnormal and remain of very small size; some of 

 these abnormal embryos practically complete their development — 

 producing "monsters" in which the head and eyes are most often 

 affected. That such abnormal embryos and monsters arise only 

 from very young embryos, of 2.2 days or less, is indicated by the 

 data of Table I. 



table 1. 



Showing that the Production of Developmental Abnormalities and "Mon- 

 sters" by Increased Oxygen Pressures (95.8 Per Cent., during 23 

 Hours) is Closely Limited to the Youngest Embryos Treated. 



Age (in 

 Days) of 

 Embryo. 



Killed. 



Sur- 

 vived. 



Normal or Abnor- 

 mal (for Survivors). 



Age (in 

 Days of 

 Embryos. 



Killed. 



Sur- 

 vived. 



Normal or Ab- 

 normal (for 

 Survivors) . 



7-5 





+ 



Normal 



4-2 



* 



* 





7-5 



* 



* 





4.2 



* 



* 





7-2 



* 



* 





4.0 



* 



* 





7.0 



* 



* 





3-5 



* 



* 





7.0 





■ + 



Normal 



2-5 





+ 



Normal 



6-5 



* 



* 





2-5 



* 



* 





6.2 



* 



* 





2-5 



* 



* 





6.2 



* 



* 





2.4 



I 



I 





6.0 





+ 



Normal 



2.2 



* 



* 



Abnormal 



6.0 





+ 



Normal 



2.0 



* 



* 





6.0 





+ 



Normal 



2.0 



2 



2 



Abnormal 



5-5 



* 



* 





1-5 



+ 







5-5 



* 



* 





1.2 



2 



2 



Abnormal 



5-5 



* 



* 





1.2 



2 



2 



Abnormal 



5-5 



* 



* 





1.2 



3 



3 



Abnormal 



5 2 



* 



* 





1.0 



2 



2 



Abnormal 



5-2 



* 



* 





1.0 



* 



* 





5-0 





+ 



Normal 



1.0 



* 



* 





5-0 





+ 



Normal 



0.5 



? 





Abnormal 



5-0 





+ 



Normal 



0.5 



? 



? 



Abnormal 



4-5 



* 



* 





0.0 





+ 



Normal 



4.2 



* 



* 





0.0 



? 



? 



Abnormal 



4.2 



* 



* 





0.0 





+ 



Normal 



* Embryo alive at end of experiment but died soon afterward. 



1 Hemoglobin nearly or quite absent, heart beating 50 hours after experiment. 



* Hemoglobin nearly or quite absent, heart beating 74 hours after experiment. 

 3 Hemoglobin nearly or quite absent, heart beating 100 hours after experiment. 



