GLOSSARY 



663 



Am'ni-on (Gr. amnos, lamb). The innermost 

 membrane which encloses the embr)o in 

 reptiles, birds, and mammals. 



Am'ni-o"ta (N.L. amniotes). A group of verte- 

 brates — reptiles, birds, and mammals — that 

 develop an amnion and an allantois. 



A-moe'boid (Gr. amoebe, change). Pertaining 

 to cell movements resembling those of the 

 amoeba. 



Am"phi-as'ter (Gr. amphi, both sides of; aster, 

 star). The figures produced in the cytoplasm 

 by the two asters and the spindle in the 

 di\iding of a nucleus by mitosis. 



Am-phib'i-a (Gr. amphi, of both kinds; bios, 

 life). A class of vertebrates that hatch as gill- 

 breathing larvae and usually metamorphose 

 into lung-breathing adults. The frog, toad, 

 and salamander are examples of the class. 



Am-phib'i-ous (Gr. amphi, both; bios, life). 

 Pertaining to animals capable of living either 

 in water or on land, such as a toad. 



Am'phi-coe"lous (Gr. amphi, both; koilos, hol- 

 low). A structure that is concave at both 

 ends; applied to some vertebrae. 



Am-pul'la (L. diminutive of amphora, jar). A 

 small bladder-shaped enlargement. Water 

 sacs attached to the tube feet of echino- 

 derms. 



Am'y-lop"sin (L. amyl, starch; Gr. trypsin, to 

 wear down). A pancreatic amylase. An 

 enzyme produced by the pancreas, which 

 acts on carbohydrates. 



An-ab'o-lism (Gr. ana, up; bole, stroke). The 

 constructive phase of metabolism in which 

 the cells build protoplasm from food mate- 

 ials. 



A-nal'o-gous (Gr. ana, up; logos, ratio, propor- 

 tion). Parts similar in function, but not 

 necessarily alike in their genetic relation- 

 ship. 



An-am'ni-o"ta (Gr. a, not; amnion, inner 

 membrane around the fetus). A group of 

 vertebrates having no amnion. It includes 

 cyclostomcs, fishes, and amphibia. 



An'a-phase (Gr. ana, up; phasis, appearance, 

 aspect). The stage in mitosis when chromo- 

 somes move from the equatorial plate to the 

 opposite ends of the mitotic spindle. 

 A-nas'to-mo"sis (Gr. ana, up, back; stoma, 

 mouth). A union or joining together, as of 

 two or more blood vessels, nerves, or other 

 structures. 



A-nat'o-my (Gr. ana, up; temnien, to cut). The 

 study of the structure of animals and 

 plants. 



An'i-mal hem'i-sphere (L. animalis, from 

 anima, life. Gr. hemi, half; sphaira, sphere). 

 That part of the egg composed of acti\e ani- 

 mal cells. 



An'ky-lo"sis (Gr. ankyios, crooked) . A union or 

 knitting together of two or more bones, or 

 parts of bones. 



An-neri-da (L. annulus, ring; Gr. eidos, form). 

 The plnlum to which the segmented worms 

 such as the earthworms belong. 



An-ten'na (L., a sail yard). A movable sense 

 organ on the head of insects, myriapods, and 

 crustaceans. Insects and myriapods have one 

 pair each, crustaceans often two pairs each. 



An-ten'nules (L. diminutive of antenna). 

 Many-jointed feelers found on some arthro- 

 pods and located near the antennae; some- 

 times called the first antennae. 



An-te'ri-or (L., foremost). Pertaining to the 

 front or head end of an animal. 



An'trum (L., antrum, cavity). A cavity or 

 chamber, referring especially to one within 

 a bone. 



A'nus (L., ring). The posterior opening of the 

 digestive tract. 



A-or'ta (Gr. aorte, the great artery). A large 

 artery which leaves the heart. 



Ap'er-ture (L. aperire, to uncover). An orifice 

 or opening. 



Ap'i-cal (L. apex, summit). Referring to the 

 end or outermost part, as of a conical struc- 

 ture. 



Ap'o-neu-ro"sis (Gr. apo, from; neuron, 

 sinew). A broad fibrous sheet of tissue or 

 fascia attaching a muscle. 



Ap'o-pyle (Gr. apo, away; pyle, gate). A pore 

 leading from the chambers into the central 

 cavity (spongocoel) in sponges. 



Ap-pend'age (L. ad, to; pendere, to hang). A 

 portion of the body which projects and has a 

 free end, such as limbs. 



Ap'pen-dic"u-lar skd'e-ton (L. ad, to; pendere, 

 to hang. Gr. skeletos, hard). That part of a 

 vertebrate which consists of the limbs and 

 limb girdles. 



Ap-pen'dLx (L. ad, to; pendere, to hang). See 

 \crmiform appendix. 



Ap'ter-ous (Gr. a, without; pteron, wing). 

 Wingless. 



