THE CONTROL OF LIFE 97 



In the remarkable experiments of Loeb 

 it was found that merely treating unfer- 

 tilized sea urchin eggs for a short time 

 with butyric acid, followed by somewhat 

 concentrated sea water, caused them to 

 develop just as if fertilized by sperm. 



Loeb also found that by adding a small 

 amount of alkali to the sea water he 

 could cause the sperm of the starfish to 

 enter the egg of the sea urchin and thus 

 produce a hybrid which does not occur 

 in nature. 



We may recall some of the eflFects of 

 special kinds of food. It is well known 

 that bees create a queen by feeding with 

 a special substance called "royal jelly." 

 The other females which do not receive 

 this food become the sterile "workers." 

 A very interesting experiment was made 

 by Marchal upon certain wasps. The 

 workers or sterile females attend to the 

 feeding of the larvae. Marchal took away 

 the larvae but continued to provide the 

 workers with food. As there were no lar- 

 vae to feed they ate it themselves and as 



