GLOSSARY. 725 



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 



determined. 

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



which is composed of fine strands of protoplasm. 



Bacteria. A class of minute fungi, which occur in all decomposing 

 animal or vegetable substances. 



Bilirubin. The red coloring-matter of the bile of man and carni- 

 vora. 



Biliverdin. The greenish coloring-matter of the bile of herbivorous 

 animals. 



Binocular. Pertaining to vision with two eyes. A combination of 

 the effect of two retinal impressions by means of which the 

 appearances of distance and solidity are arrived at. 



Biology. The science of life. 



Blastoderm. The primitive cellular membrane formed by the seg- 

 mentation of the ovum, in a part of which the embryo is devel- 

 oped. 



Blood-pressure. The force exercised by the blood against the walls 

 of the vessels. It is very great in the arteries, and therefore 

 causes a constant stream through the capillaries to the veins. 



Canaliculi. Minute channels which connect the small cell-spaces 

 or Iacuna3 of bone with each other, and contain protoplasmic 

 filaments uniting the neighboring cells. 



Carbohydrates. Compounds of carbon, hydrogen, and oxygen, in 

 which the oxygen and hydrogen exist in the proportions requi- 

 site to form water. 



Cardiograph. An instrument by means of which the heart's im- 

 pulse is transmitted, through an air tube, from a tambour on 

 the chest-wall to another which makes a record on a moving 

 surface by means of a lever. 



Catelectrotonus. A peculiar electric state of a nerve in the region 

 where a current passing through it leaves the nerve, ie., near 

 the negative pole. 



Cathode. The negative pole or electrode ie., the one by which the 

 electric current leaves a substance through which it is passing. 



Centrifugal. Efferent. 



