GLOSSARY 527 



Pol'-len. The male sex cells of flowering plants. 



Pol-y-dac'-tyl-ism. The condition of having more than the 

 normal number of digits on hands or feet. 



Pol-y-hy'-brid. The offspring of parents differing in more 

 than three characters. 



Pre-for-ma'-tion. The doctrine that the fully formed organ- 

 ism exists in the germ, and that development is merely 

 its unfolding. 



Pre-in-duc'-tion. A modification of the second filial gener- 

 ation caused by the action of environment on the germ 

 cells of the parental generation. (Woltereck). 



Pre-in-her'-it-ance. The transmission of characters developed 

 in a previous generation. 



Pre-po'-ten-cy. The preponderance of one parent over the 

 other in the transmission of hereditary characters. 



Pri'-mates. The highest order of mammals, including monkeys, 

 apes, and man. 



Primitive Sex Cells. The earliest recognizable progenitors 

 of the sex cells in development. 



Pro'-te-in. Complex organic substances containing nitrogen, 

 e.g. white of egg. 



Pro-te'-nor. A genus of the true bugs. 



Pro'-to-plasm. The living material of an organism. 



Pro-to-zo'-a. The simplest animals, usually consisting of a 

 single cell. 



Py-lo'-rus. The narrow opening between stomach and 

 intestine. 



Recessive character. An inherited character which remains 

 undeveloped when mated with a dominant character. 



Reduction-Division. That maturation division in which the 

 number of chromosomes is halved. 



Reflexes. Relatively simple, automatic responses. 



Response. Any activity of an organism called forth by a 

 stimulus. 



Reversions. The sudden reappearance of long-lost racial 

 characters. 



Segregation. The separation of contrasting parental char- 

 acters in the offspring of hybrids. 



