Glossary 359 



O'-VUM. The female sex cell. 



OX-Y-CHRO'-MA-TIN. That portion of the chromatin which does not form 

 chromosomes. 



PAN-GEN'-E-SIS. The hypothesis proposed by Darwin that every cell of the 

 body gives off minute germs, "gemmules," which then collect in the 

 sex cells. 



PAR-A-ME'-CI-UM. A ciliated protozoan. 



PAR-THE-NO-GEN'-E-SIS. Development of an egg without previous fertili- 

 zation. 



PARTICULATE INHERITANCE. Galton's term for that kind of inheritance in 

 which certain characters are derived from one parent and others from 

 the other parent, i.e., Mendelian Inheritance. 



PA-THOL'O-GY. The science which deals with disease. 



PHE'-NO-TYPE. The developed type in which some of the hereditary pos- 

 sibilities are realized while others remain undeveloped. "Developed, 

 measurable realities" (Johannsen). 



PHY-LOG'-E-NY. Evolution of a race or species. 



PHYL-LOX'-E-RA. A genus of plant lice. 



PHY'-LUM. One of the chief sub-divisions of the animal kingdom. 



PHYS-I-OL'-O-GY. The science which deals with function. 



PLAS'-TO-SOMES. Threads or granules in the cytoplasm which are colored 

 by certain dyes. 



POLAR BODIES. Two minute cells which are separated from the egg in its 

 two maturation divisions. 



PO-LAR'-I-TY. The condition where two poles of a body differ; in eggs the 

 two poles are the animal (formative) and the vegetative (nutritive). 



POL'-LEN. The male sex cells of flowering plants. 



POL-Y-DAC'-TYL-ISM. The condition of having more than the normal num- 

 ber 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 organism exists 

 in the germ, and that development is merely its unfolding. 



PRE-IN-DUC'-TION. A modification of the second filial generation caused 

 by the action of environment on the germ cells of the parental genera- 

 tion. (Woltereck.) 



PRE-IN-HER'-IT-ANCE. The transmission of characters developed in a pre- 

 vious generation. 



PRE-PO'-TENCY. 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. 



