GLOSSARY OF IMPORTANT TERMS 



683 



Physiology (fiz'if ol'o ji) : study of the 

 functions of plants and animals. 



Pistil : a structure in the flower con- 

 taining the ovary, in which the 

 seeds are formed. 



Pistillate : having pistils but no 

 stamens. 



Pith : the soft, spongy tissue in the 

 center of a dicotyledonous stem and 

 between the vascular bundles of a 

 monocotyledonous stem. 



Pituitary (pi tu'i ta ri) body : small 

 endocrine gland located in the base 

 of the brain. 



Placenta (pld sen'td) : absorbing organ 

 which nourishes the embryo. 



Plankton (plank'ton) : small plants 

 and animals which live near the 

 surface of bodies of water. 



Plasma (pl&z'md) : the colorless fluid 

 part of blood. 



Platyhelminthes (plat'i hel mm'thez) : 

 the phylum of animals to which the 

 flatworms belong. 



Pleura (ploo'rd) : the membrane 

 which covers the lungs and lines 

 the cavity _containing them. 



Plumule (ploo'mul) : the part of the 

 embryo above the cotyledons which 

 develops into the stem and leaves. 



Pollen grain: a small cell in the 

 stamens of a flower which con- 

 tains the sperm nucleus or male 

 gamete. 



Pollination (pol'i na'shwn) : the trans- 

 fer of pollen from the anther to the 

 stigma. Self-pollination is transfer 

 between parts in the same flower ; 

 cross-pollination is transfer between 

 different flowers, or between flowers 

 on different plants. 



Polyp (pol'ip) : a simple coelenterate, 

 as a sea anemone or a single coral 

 individual. 



Posterior (pos te'ri er) : nearer the 

 last or tail end of an animal. 



Precipitins (pre sip'i tinz) : antibodies 

 or precipitating substances formed 

 in the blood as a reaction to the 

 introduction of certain foreign pro- 

 teins. 



Primary root : the main root of a 

 plant. 



Proboscis (pro bos'is) : a slender suck- 

 ing tube found in insects. 



Proglottids : reproductive body seg- 

 ments of a tapeworm. 



Proleg: an unjointed abdominal 

 appendage of insect larvae. 



Protective resemblance : the likeness 

 of living organisms in color or form 

 to their immediate surroundings, 

 thus securing protection from attack 

 of enemies. 



Proteins (pro'teinz) : nitrogenous com- 

 pounds found in the bodies of plants 

 and animals; a class of nutrients 

 composed of nitrogen, carbon, 

 hydrogen, and oxygen, together 

 with other elements in some cases. 



Prothallium (pro thal'I um) : the re- 

 duced gametophyte of ferns. 



Protoplasm (pr5'to plaz'm) : the liv- 

 ing substance of plants and animals. *• 



Protozoa (pro'to zo'd) : a phylum con- 

 taining one-celled animals. 



Pseudopodium (sti'do po'di um) : a 

 projection of protoplasm used for 

 locomotion in protozoans. 



Pteridophyta (ter'i dof'i ta) : a phy- 

 lum of plants to which the ferns 

 belong. 



Ptomaine (to'ma m) : poisonous mate- 

 rial probably the result of decompo- 

 sition of proteins. 



Ptyalin (ti'd lln) : an enzyme in the 

 saliva, which changes starchy foods. 



Pulmonary (puTmo na ri) : pertaining 

 to the lungs. 



Pulvinus (pul vi'nws) : a special motor 

 organ at the base of the petiole of a 

 leaf. 



Pupa (pu'pd) : the quiescent stage in 

 insect development preceding the 

 adult. 



Pylorus (pi lo'rws) : the opening from 

 the stomach into the intestine. 



Quarantine (kwor'an ten) : isolation 

 of the sick to prevent the spread of 

 communicable disease. 



Recessive : a Mendelian term applied 



to that unit character which is 



subordinate to another. 

 Reflex : simplest type of nervous 



response. 

 Regeneration (re jen'er a'shun) : the 



growing again of a part of an animal 



which has been lost. 



