GLOSSARY OF TECHNICAL TERMS xxxv 



applied to hermaphrodite organisms in which the female 



organs mature before the male. 

 PROTOPLASM (Gr. irp&Tos, first ; 7rAao>ta, formative material), the 



essential constituent of all living bodies ; " the physical 



basis of life." 

 PROTOZOON (Gr. -p^ros, first ; Cyov, animal), a unicellular 



animal. 

 PSEUDOPODIUM(GI*. \lfvbi]s, false; TTOVS, foot), a temporary, irregular 



protoplasmic projection from a naked cell, generally used as 



an organ of locomotion (e.g., in Amoeba). 

 PYRENOID (Gr. itvpriv, fruit stone ; ei5os, form), a starch-forming 



proteid body, found in certain cells. 

 RADIUS (Lat., spoke), one of the bones of the forearm. 

 RECAPITULATION HYPOTHESIS, the theory in accordance with which 



an individual organism repeats its ancestral history in its 



own development. 

 RECEPTOR (Lat., receiver), an organ which receives stimuli, a sense 



organ. 

 REGRESSION, FILIAL (Lat. regressus, a going back), a return on 



the part of the offspring of exceptional parents towards the 



average condition of the species. 

 RESPIRATION (Lat. respiratio, breathing), essentially the interchange 



of the two gases, oxygen and carbon dioxide, the former being 



taken in by the organism (or tissue) and the latter given out. 

 REVERSION (L&t.reversio, a turning back), the sudden reappearance 



of some long-lost ancestral character. 

 RODENTS (Lat. rodere, to gnaw), animals of the order Rodentia 



(e.g., rabbits, mice). 

 ROSTELLUM (Lat. dim. rostrum, beak, snout), one of the three 



stigmas of an orchid modified to form a kind of cement gland. 

 ROTIFERS (Lat. rota, wheel ; ferre, to carry), wheel animalcules, 



a group of minute aquatic worms with cilia arranged like 



wheels. 

 SAPROPHYTIC (Gr. (Tempos, putrid ; AUTO'S, growing), living on dead 



organic matter. 



SARCODE (Gr. <rdp, flesh ; et5os, form), an old term for proto- 

 plasm. 



SCAPULA (Lat., shoulder blade), the shoulder blade. 

 SECRETION (Lat. secretus, separate), a useful substance separated 



or secreted by some special organ (gland) ; or the process 



involved therein. 



