1U2 TEMPERATURE AND EMBRYONIC DEVELOPMENT 



ANALYSIS OF RADICAL TEMPERATUBE CHANGE EFFECT ON GASTRULATION 



3. Effect of temperature change on subsequent rate of development : It has teen sug- 

 gested (Buchanan, 19^+0 ; Ryan, 19^+1) th&t when eggs or embryos are subjected to 

 low (or high) temperatures, within the viable range, and then returned to the con- 

 trol (normal) temperature, that the effect on the rate of development is such that 

 temporary cold retardation (for instance) causes subsequent' acceleration so that 

 the experimentals may even pass the controls. To test this concfept, the following 

 procedure is suggested. 



Provide adequate space at a controlled l8°C. environment for 10 finger bowls. In- 

 seminate eggs of Eana pipiens, and at the 2-cell stage separate them into groups of 25 per 

 finger bowl of 50 cc. of Standard Solution at l8°C. Place two (2) of these finger bowls 

 at the control temperature and four each at the upper limit (29°C.) and at the lower limit 

 (10°C.)' At Intervals of 6, 2k, 56, and kS hours remove a finger bowl of eggs from each 

 of the extreme temperatures and place it at the control temperature of l8°C. There should 

 be no radical or sudden change in temperature, rather a gradual adjustment within the 

 original medium. Record the stage of development of 30$ of the embryos at daily intervals 

 up to about 12 days (when feeding begins). 



