GLOSSARY 431 



AUTONOMIC SYSTEM. System of outlying ganglia and nerves which 

 communicates with the central nervous system via the roots of 

 the spinal and cranial nerves. Innervates chiefly the involuntary 

 muscles of blood vessels, digestive organs, etc. Sympathetic 

 system. 



AXON. A nerve fiber conducting impulses away from the cell body. 

 Dendrites conduct toward the cell body. See Neuron. 



BAST. The phloem portion of a vascular bundle. 



BIENNIAL. A plant which completes its life history in two years, 

 usually reproducing in the second. 



BILE DUCT. Tube which conveys the secretions (bile) of the liver 

 to the small intestine. Usually unites with the pancreatic duct 

 to form a common duct which enters the intestine. 



BINARY FISSION. The division of a cell, especially a unicellular 

 organism, into two daughter cells; e.g., in Paramecium. 



BINOMIAL NOMENCLATURE. The accepted scientific method of 

 designating organisms by two Latin or Latinized words, the 

 first indicating the genus and the other, the species. E.g., the 

 Dog, Canis familiaris; Man, Homo sapiens. 



BIOGENESIS. The established doctrine that all life arises from pre- 

 existing living matter. See Abiogenesis. 



BIOLOGY. The study of the manifestations of matter in the living 

 state. 



BIPARENTAL. Derived from two progenitors, male and female, e.g., 

 in sexual reproduction. See Uniparental. 



BLASTOCOEL. The cavity within the blastula. Segmentation cavity. 



BLASTOPORE. The opening to the exterior from the enteric pouch 

 of a gastrula. 



BLASTULA. The stage following cleavage when the cells are ar- 

 ranged in a single layer to form a hollow sphere. 



BLENDING INHERITANCE. Apparent fusion of parental characters 

 in the offspring so that a more or less intermediate condition 

 arises. E.g., skin color of mulattoes. 



BLOOD CORPUSCLES. Detached cells present in the fluid plasma of 

 the blood. Two principal kinds, red and white. 



BUCCAL CAVITY. Mouth cavity. 



