TEMPERATURE AND EMBRYONIC DEVELOPMENT 



14l 



2. Suh .lection of pre-sastrula ata^e to radical temperatures : The forcea involved in 

 gaatrular movements are no doubt at work prior to any indication of these morpho- 

 genetic movements. It la necessary, therefore, in this study to secure eggs (Sana 

 pipiens) at stage #8 or #9 and place these egga at the supra-maximal and suh- 

 minimal temperatures, as previously determined, to see whether gaatrulation is 

 subject to temperature interference. 



In a manner similar to (1) on the preceding page, prepare 25 eggs per finger bowl of 

 50 cc. Standard Solution and leave them at the controlled room (l8°C.) temperature until 

 they reach stage #8 or #9. In the meantime, provide abundant Standard Solution at k°C. 

 and at 55°'^-, into which the egga can be tranafered for intervals of 1, 2, 6, and 2k houre. 

 Eecord the effect on gaatrulation and subsequent development in the following table. 



PRE-GASTHULATION RADICAL TIMPEBATUBE TREATMENT 

 STAGE* AND CONDITION OF EMBRYOS 



SPECIES: 



TIME IN DAYS 



Most advanced stage of at least 50^ of the embryos. 



