GLOSSARY 



685 



Res'pi-ra"tion (L. re, again; spirare, to 

 breathe). The actual use of oxygen by the 

 cell; this is usually termed cellular or internal 

 respiration. Compare with External respira- 

 tion. 



Re-sponse' (L. re, again; spondere, to promise). 

 Reaction to a stimulus cither internal or ex- 

 ternal. 



Rest'ing cell. See Interphase cell. 



Ret'i-na (L. rete, net) . The light-sensitive layer 

 of an eye. 



Rhab'dites (Gr. rhabdos, rod). Rodlike bodies 

 in the epidermis of certain flatworms, as in 

 the planaria. 



Rhab'dom (Gr. rhabdos, rod). A rodlike struc- 

 ture formed of the inner surfaces of adjacent 

 sensory cells in the ommatidium of a com- 

 pound arthropod eye. 



Rhab'do-mere (Gr. rhabdos, rod; Gr. meros, 

 part). The receptive area of a retinal cell 

 that is one of the component parts of the 

 rhabdom. 



Rh fac'tor. A kind of antigen found in some 

 red blood corpuscles. An antigen first found 

 in the red blood cells of the rhesus monkey, 

 hence the name Rh positive and Rh nega- 

 tive, denoting presence or absence of this 

 factor. 



Ri'bo-fla'vin. Constituent of the vitamin B 

 complex, important in cell metabolism. 



Ros'trum (L. rostrum, beak). The anteriorly 

 projecting beak, as in the crayfish. 



Ro'ta-tor (L. rota, wheel). The type of volun- 

 tary muscle which brings about the rotary 

 motion of one part of an organism on 

 another. 



Ru'gae (L., wrinkles). Ridges or folds as in the 

 hning of the vertebrate stomach. 



Ru'mi-nant (L. rumen, throat). A cud-chewing 

 mammal as the cow. 



Sap'ro-zo"ic (Gr. sapros, rotten; zoion, living 

 being). Pertaining to an animal which lives 

 upon decaying organic matter. 



Sar'co-lem"ma (Gr. sarx, flesh; lemma, cover- 

 ing). A thin membrane surrounding a skele- 

 tal or striated muscle cell. 



Sar'co-plasm (Gr. sarx, flesh; plasma, liquid). 

 The protoplasmic substance of skeletal mus- 

 cle cells. 



Scao'u-la (L., shoulder blade). Shoulder blade 

 m a vertebrate. 



Sci'cn-tif'ic nieth'od (L. scientia, knowledge; 

 Gr. metahudos, road, way). The scientific 

 method involves, primarily, the formulation 

 of ideas (hypotheses) on the basis of a rela- 

 tively small amount of knowledge, then test- 

 ing the correctness of the ideas by securing 

 more facts by obser\ation, arranging the facts 

 observed in some orderlv manner to deter- 

 mine relationships, and then drawing logical 

 conclusions. 



Sci'en-tif'ic name (L. scientia, knowledge. Gr. 

 onoma, name). The binomial or trinomial 

 designation of an animal. 



Scle'rite (Gr. skleros, hard). A hardened body 

 wall plate bounded by sutures, as in the 

 arthropods. 



Sco'lex (Gr. skolex, worm). The small knob- 

 like "head" at the anterior end of a tape- 

 worm. 



Se-ba'ceous glands (L. sebum, tallow, grease. 

 L. glans, acorn ) . Small skin glands, usually 

 found in connection with the hair follicles 

 of the mammals. They produce an oily se- 

 cretion which lubricates the skin and hair. 



Se'bum (L. sebum, tallow) . The fatt}' secretion 

 of the sebaceous glands. 



Sec'ond-ary sex'u-al char'ac-ters. Characters 

 other than the sex glands (gonads) and re- 

 lated organs in which males and females of 

 a species differ. 



Se-cre'tion (L. secretio, from secemere, to 

 separate). The production by the proto- 

 plasm of a substance of use to the organism; 

 also the substance produced. 



Seg'ment (L. segmentum, piece cut off). One 

 part of a metameric animal. 



Sclf'-fcr-ti-li-za'tion. Fertilizing an egg by a 

 sperm from the same indi\idual. 



Se'men (L. serere, to sow). I'luid which carries 

 the sperms in the males of most animals. 



Sem'i-cir"cii-lar ca-nals' ( L. semi, half; circulus, 

 circle). Canals in the vertebrate ear, asso- 

 ciated with the sense of equilibrium. 



Sem'i-nal (L. semen, seed). Pcrtannng to sper- 

 motozoa. 



Sem'i-nal rc-cep'ta-cles (L. semen, seed. L. 

 recipere, to receive). Saclike organs in several 

 types of animals, which reccixe and store 

 sperms after their release. They are con- 

 sidered a part of the female genital system. 



Sem'in-al vcs'i-cles (L. semen, seed. L. vesica, 

 bladder). Saclikc organs in several t}pcs of 

 animals in which the seminal fluid is stored 



