GLOSSARY 365 



Albumen (albu'men). A protein substance having certain properties, such as 

 solubility in water, precipitability in strong acids, etc. 



Alimentary {al' i men' ta ri). Pertaining to digestion or to the digestive tract. 



Alternation of generations. See metagenesis. 



Altricial {al Irish' al). Hatched in a weak, helpless condition; said of certain birds. 



Alveolar {al ve' o ler). Of the nature of an emulsion. 



Alveolar gland {al ve' o ler). A gland in which the lumen is inflated at certain points. 



Alveolus {alve' o lus) {pi., alveoli). One of the separate droplets of an emulsion, as 

 in protoplasm. Also one of the minute air spaces in a lung. 



Ambulacral (a??;/ hula' kral). Resembling an alley; applied to the grooves beneath 

 the arms of a starfish, in which the tube-feet are located. 



Ambystoma {am his' to ma). A genus of salamanders. A. tigrinum {tigri'num), 

 the common tiger salamander. 



Amino-acid {am' i no as' id). One of a number of organic acids containing the NH2 

 radical and having certain chemical properties. These acids enter into the com- 

 position of all proteins and are produced by the splitting of proteins. 



Amino radical {am' i no). The radical NH2 found in amino acids. 



Amitosis {a' mi to' sis) . Cell division not involving the formation of chromosomes or a 

 spindle. 



Ammonite {am'monite). An extinct cephalopod having a coiled shell and com- 

 plicated foliaceous sutures; so-called from the genus Ammonites. 



Amoeba (a me' ha). A genus of one-celled animals, a protozoon of the class Rhizop- 

 oda. A. diplomitotica {di-p' lo mi tot' i ka) ; A. proteus {pro' te us) ; A. verrucosa 

 {ver' ru ko' sa). 



Amoeboid (a me' hold). Resembling Amoeba; as, amoeboid movement. 



Amphiaster {am' fi as' ter). The figure produced by two asters and the connecting 

 spindle in a dividing cell. 



Amphibia {am fib' i a). A class of Vertebrata embracing the frogs, toads, salamanders, 

 and some others. For definition see Chapter XII. 



Amphicoelous {am' fi see' lus). Having both ends of the centrum concave; said of 

 vertebra?. 



Amphineura {am' fi nu' ra). A class of Mollusca, the members of which are bilater- 

 ally symmetrical, have a shell of eight pieces or no shell at all, and many pairs of 

 gills. Chiton is an example. 



Amphioxus {am' fi oks' us). A primitive fish-like animal belonging to the subphylum 

 Cephalochorda of the Chordata. 



Amplexus {am pleks' us). The clasping of a female by the male before or while the 

 eggs are fertilized outside of the body, or while the spermatozoa are being de- 

 posited to be later secured by the female. 



Amylolitic {am' i lo lit' ik). Carbohydrate-splitting. 



Amylopsin {am' i lop' sin) . A starch-digesting enzyme produced by the pancreas. 



Anabolism {an ah' o liz'm). The aggregate of constructive processes comprised 

 in metabolism. 



Analogous {an al' o gus). Similar in function. 



Anaphase {an' a faze). Any stage of cell division during the passage of the chromo- 

 somes from the middle to the ends of the spindle. 



Anatomy {an at' o mi). The science which treats of the structure of animals and 



