862 Appendix 



Unity of an organism, constant integration of various structural and physiologic 

 components of an organism so that it will be a unit, structurally and func- 

 tionally. 



Urea (u-re'a) (Gr. ouron, urine), nitrogenous waste material of animal metab- 

 olism. 



Ureter (u-re'ter) (Gr. oureter, ureter), tube carrying urine from kidneys to 

 bladder or to cloaca. 



Urethra (u -re' thra) (Gr. ourethra, urethra), tube carrying urine for bladder to 

 outside. 



Uriniferous tubules (u ri -nif er us), unit of urinary system of higher animals 

 consisting of coiled tubes and a capsule. 



Urogenital (urinogenital) (u ro -gen' i tal) (Gr. oura, urine; gignesthai, to pro- 

 duce), the organs of both urinary and reproductive systems taken collec- 

 tively. 



Uropod (u'ropod) (Gr. oura, tail; pons, appendage), modified swimmeret on 

 either side of the last abdominal segment of a crayfish. 



Urostyle (u'ro stile) (Gr. oura, tail; style, pillar), last rodlike bone of frog spinal 

 column. 



Uterus (u'terus) (L. uterus, belly, womb), enlarged part of oviduct; in female 

 mammals an organ for containing and nourishing the developing young 

 before birth. 



V 



Vaccine (vak' seen) (L. uacca, cow), the virus of cowpox administered to build 

 immunity against smallpox. The term is more generally applied, although 

 incorrectly, to many types of so-called "shots." 



Vacuole (vak'uole)' (L. vaccum, empty), space for receiving something. 



Vagina (va-ji'na) (L. vagina, sheath), in female mammals a tube leading from 

 the uterus to the exterior. 



Variation (var i -a' shun) (L. variare, change), differences shown by individuals 

 of the same species, etc. 



Vas deferens (plural, vasa deferentia) (vaz; def er ens) (L. vasa, vessel; de, down; 

 fero, to bear), tube to carry sperm to the exterior. 



Vasa efferentia (vaza; ef er -en' sha) (L. vasa, vessel; ex, out; ferro, to bear), 

 tubes carrying sperm from testes to the vasa deferentia. 



Vascular (vas' ku lar) (L. vasculum, little vessel), pertaining to vessels, usually 

 blood vessels. 



Vascular bundle, structure composed of vessels (xylem and phloem) for conduct- 

 ing liquids in higher plants. 



Vasomotor nerves (vas o -mot' er) (L. vasa, vessel; movere, to move), nerves con- 

 trolling the caliber of the arteries by the contraction and expansion of 

 muscles in their walls. 



Vegetal pole (veg' e tal) (L. vegetare, enliven), pole of a cell where the rate of 

 metabolism is lower than that at the animal pole. 



Vegetative reproduction, asexual reproduction by such methods as grafting, cut- 

 tings, fragmentation, etc. 



Vein (L. vena, vein), vessel carrying blood toward the heart; vascular bundle of 

 a leaf. 



