720 GLOSSARY. 



Amylopsin. A ferment in the pancreatic juice, which converts starch 

 into sugar. 



Analgesia. A condition of the nervous centres in which pain cannot 

 be felt, but ordinary tactile and other sensations remain un- 

 impaired. 



Analysis. A separation into component parts ; the splitting up of a 

 chemical compound into its constituents. 



Anastomoses. The direct union of blood vessels without the inter- 

 vention of a capillary network. 



Anelectrotonus. A peculiar electric condition of a nerve, resulting 

 from the passage of a current through the nerve, but confined to the 

 region where the current enters, i. e., the neighborhood of the posi- 

 tive pole. 



Anode. The positive pole or electrode, i. e., the pole by which the 

 electric current enters a substance. 



Apnoea. A state of cessation of the breathing movements from non- 

 excitation of the respiratory nerve centre on account of an unusually 

 arterial state of the blood. 



Area opaca. The outer zone of the blastoderm from which the foetal 

 membranes are developed. 



Area pellucida. The central spot of the blastoderm from which the 

 embryo chick is developed. 



Arteriole. A small artery ; usually applied to those vessels the walls 

 of which are largely composed of muscle tissue. 



Arthroses. Movable joints which have a synovial membrane. 



Asphyxia. A term meaning, literally, cessation of the pulse, such 

 as occurs from interruption of respiration, now commonly used as 

 synonymous with suffocation. 



Assimilation. The chemical combination of new material (nutriment) 

 with living tissues. This forms the most characteristic property of 

 living matter. 



Astigmatism. Unevenness of the refracting surfaces of the eye ; 

 when engaging the entire cornea, it is called "regular," and affect- 

 ing a local part, " irregular," astigmatism. 



Atoms. The ultimate indivisible particles of matter. 



Atrophy. A wasting from insufficient nutrition. 



Automatic. Self- moving i. e., acting without extrinsic aid ; a term 

 applied to the independent activity of certain tissues (such as the 

 nerve centres), the exciting energies of which are not readily deter- 

 mined. 



Axis cylinder. The essential conducting part of a nerve fibre, which 

 is composed of fine strands of protoplasm. 



