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TEMPERATURE AND EMBRYONIC DEVELOPMENT 



THE EFFECT OF TEMPORARY DRASTIC TEMPERATURE CHANGE 



ON DEVELOPMENT 



Three temperatures are to be used for these ohservations, but two of them are to be 

 beyond the normal range of viability. Prepare an incubator which is controlled at about 

 55° to 55°C. and a refrigerator at or near 0°C. Place four finger bowla, each with 50 cc. 

 of the appropriate medium, at each of these temperatures. If possible, adjust the control 

 temperature at IS'-'C. comparable to the Shumway series. 



1. Pre-cleavage exposure to radical temperature : Inseminate healthy eggs of Eana 

 pipiens and, after flooding and allowing them to swell (about 1 hour) cut them in- 

 to clusters (5 to 10 each) and place 25 in each of the 10 finger bowls {k at 0°C., 

 2 at l8°C., and h at 55°C.). Eecord the exact time on each bowl with China mark- 

 ing pencil. At exactly 1, 2, 6, and 2k hours thereafter remove one finger bowl 

 from each of the two radical temperatures, and place it in the environment of the 

 18°C. control eggs (providing it is large enough and adequately controlled to take 

 care of the drastic temperature invasion). Note the condition of the eggs in each 

 bowl at the time of removal from the drastic temperatures, and the condition 

 (stage) of the controls. Follow the subsequent development of all treated and 

 control eggs to determine the effect of these radical temperatures at this early 

 stage of development. 



PEE- CLEAVAGE RADICAL TBtPERATUEE TREATMENT 

 STAGE* AND CONDITION OF EGGS ( EMBRYOS) 



SPECIES TIME 



HOURS 



DAYS 



* 50^ of eggs. 



