494 APPENDIX 



Biocoenosis. An association of diverse organisms forming a natural 



ecological unit in which there is more or less interdependence. 

 Biogenesis. The established doctrine that all life arises from preexisting 



living matter. See Abiogenesis. 

 Biogenetic Law. See Recapitulation Theory. 

 Biology. Study of matter in the living state, and its manifestations. 

 Biparental. Involving two progenitors, male and female. 

 Biramous. Comprising two branching parts; e.g., abdominal appendages 



(swimmerets) of the Crayfish. 

 Blastocoel. The cavity within the blastula. Segmentation cavity. 

 Blastopore. The opening to the exterior from the enteric pouch of a 



gastrula. 

 Blastostyle. Central axis of an individual (gonangium) of a Hydroid 



colony that buds medusae, e.g., in Obelia. 

 Blastula. The stage following cleavage when the cells are arranged 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. 



Calciferous Glands. Glands opening into the esophagus of the Earth- 

 worm which secrete calcium carbonate, probably to neutralize acidity 

 of food. 



Calorie. The unit of heat energy, and therefore largely of fuel value. 

 Heat required to raise 1000 grams of water through 1° C. Large calorie. 



Carrohydrates. Compounds of carbon with hydrogen and oxygen, the 

 hydrogen and oxygen typically in the same proportion as in water (H 2 0). 



Cardinal Veins. Pair of large veins returning blood from posterior part 

 of body, e.g., in Dogfish. 



Castration. Removal of the gonads, especially of the male. 



Catalysis. The inducing or accelerating of a chemical reaction by a 

 substance (e.g., an enzyme) which itself remains unchanged. 



Cell. A structural and physiological unit mass of protoplasm, differ- 

 entiated into cytoplasm and nucleus. 



Cellulose. A carbohydrate which characteristically forms the walls of 

 plant cells. 



Central Capsule. Perforated partition that separates the endoplasm 

 from the ectoplasm in the Radiolaria. 



Centrosome. A body, enclosing a minute granule, or centriole, situated 

 in the center of the aster and active during cell division. 



