526 GLOSSARY 



Or-gan-og'-e-ny. The formation of various organs of the 

 body. 



Or-tho-gen'-e-sis. The doctrine that the course of evolution 

 is definitely directed by intrinsic causes. 



O-vi-par'-i-ty. Young brought forth as eggs, i.e., in an early 

 stage of development. 



O'-vuxes. The female sex cells of flowering plants with the 

 immediately surrounding parts. 



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 pre- 

 vious fertilization. 



Particulate Inheritance. Galton's term for that kind of in- 

 heritance in which certain characters are derived from one 

 parent and others from the other parent, i.e. Mende- 

 lian Inheritance. 



Pa-thol'-'o-gy. The science which deals with disease. 



Phe'-no-type. The developed type in which some of the her- 

 editary possibilities are realized while others remain un- 

 developed. "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 king- 

 dom. 



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 maturations 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). 



