EM TARY BIOLOGY 



EXPERIMENTS IN EVOLUTION 



Mendel found that when pure-bred green-seeded peas were 

 crossed with pure-bred yellow-seeded peas, the offspring were all 

 yellow-seeded. When these hybrid plants were crossed with one 

 another, the following generation produced three yellow-seeded 

 plants to one green-seeded plant. 



Tower found that exposing the young stages of potato beetles to 

 extreme conditions of moisture and temperature produced in the 

 following generations modifications that were inherited. The results 

 of high temperature and low humidity are illustrated at the left of 

 the parent type ; the results of low temperature and high humidity 

 are illustrated at the right. 



