GLOSSARY 511 



PaE-roR-MA'-xiON. The doctrine that the fully formed organ- 

 ism exists in the germ, and that development is merely 

 its unfolding. 

 PRE-iN-Duc'-uosr. A modification of the second filial gener- 

 ation caused by the action of environment on the germ 

 cells of the parental generation. 



Pbe-po'-tek-ct. 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. 



Pao'-TE-iN. Complex organic substances containing nitrogen, 

 e.g. white of egg. 



Pro-te'-kor. 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 dominant and recessive char- 

 acters in the offspring of hybrids. 



Self Differentiation. Differentiation due chiefly to intrinsic 

 causes. 



Sensitivity. Capacity of receiving and responding to stimuli. 



Sex Chro'-mo-some. The "odd" or accessory chromosome 

 which is supposed to determine sex. 



Sex-limited. Any character which is found in one sex only. 



