GLOSSARY 921 



Telencephaloii (tel en sef a Ion), the anterior division of the vertebrate brain. 



Telolecithal (tel 6 les'i thai), type of egg with abundant yolk unequally dis- 

 tributed. 



Telophase (tel'ofaz), the final stage in mitotic divisions. 



Tentacle (ten'tak'l), flexible, armlike extension of the body of many non- 

 chordates. 



Terrestrial (ter res'tri al), a land form; living on or in the ground. 



Testis (tes'tis), male gonad. 



Thermotropism (ther mot'rfi pTz'm), response of an organism to temperature. 



Thlgmotropism (thigm6t'r6 piz'm), response of an organism to contact. 



Thoracic (tho ras'ik), of or pertaining to the thorax or chest. 



Thorax (tho'raks\ the middle region of the body. 



Threshold (thresh'old), the minimum strength of stimulus necessary to get a 

 response. 



Thrombin (throm'bm), the substance of the blood which plays an important 

 part in clotting. 



Thyroxin (thi rok'sen or -sin), the hormone which is produced by the thyroid 

 body. 



Tissue (tish'u), an organization of similar cells into a layer or group for the 

 performance of a specific function. 



Toxin (tok'sin), any poisonous substance. 



Trachea (tra'ke a),'the windpipe or a tube for conveying air to the lungs; air 

 tubes in insects. 



Trichocyst (trik'6 sist), saclike structure in the ectosarc of Paramecium. 



Triploblastic (trip 16 blas'tik), composed of three germ laj-ers. 



Trivium (triv'ium), the three anterior ambulacra of Echinodermata, collec- 

 tively. 



Trochophore (trok'ofor), a semispherical type of larva with cilia; found among 

 flatworms, annelids, mollusks, etc. 



Tropism (tro'piz'm), the movements of an organism in response to a stimulus. 



Trypanosome (trip'a n6 som), genus of parasitic Protozoa (Mastigophora) in- 

 cluding the causal agent of African sleeping sickness. 



Trypsin (trip'sin), a pancreatic enzyme which converts proteins to amino 

 acids. 



Tsetse (tset'se) fly, a species of fly which serves to transmit the causal agent 

 of African sleeping sickness. 



Tundra (tobn'dra), level plains region of the arctic region. 



Tympanum (tim'panum), cavity of the middle ear or more generally any organ 

 serving to receive sound waves. 



Umhilical (um bil'ikal) cord, the cordlike connection between the fetus and 

 the placenta. 



Umbilicus (um bil'i kus), the navel or the point of attachment of the umbilical 

 cord to the abdomen. 



Uncinate (iin'sinat), in the shape of a hook. 



Ungulate (ung'gulat\ hoofed. 



Unguiculate (unggwik'ulat), having claws. 



Urea (ure'a), a nitrogenous compound which is produced as a protein by- 

 product in metabolism. 



Ureter (ure'ter), the duct which conveys urine from the metanephric kidney 

 to the cloaca or bladder. 



Urethra (ure'thra), the duct which leads from the urinary bladder to the 

 exterior of the bodv. 



Uropods (u'ropodz), the sixth pair of abdominal appendages of a crustacean. 



Vacuoles (vak'uolz), small cavities in a cell filled with water, gasses, or oils. 

 Vagina (vaji'na), the cavity between the uterus and the external genital 

 aperture of the female in many animals. 



