GLOSSARY-INDEX 415 



posterior end, 155. 



posterior root. The branch of the spinal nerve entering on its posterior 



side and carrying impulses toward the brain, 195. 

 posterior vena cava. Same as inferior vena cava, 190. 

 potential energy, 293. 

 precoracoid, 182. 



predatory. Living by preying upon other animals, 

 premaxillary bones, 180. 

 proboscis. An elongated portion of the head of an animal, with special 



functions. 



process. Any small projection, 

 procoslous (Gr. pro = before + coilos = hollow) . Applied to vertebrae 



which are concave in front only, 

 proctodaeum, 284. 



pronation. The position of the fore arm with the palm downward, 

 pronuclei. The two nuclei, male and female, which are in the matured 



egg, ready to unite with each other, 254, 257. 

 prophase. The preliminary stage in karyokinesis, 85. 

 prostomium (Gr. pro = before + stoma = mouth). The sensitive lobe 



projecting over the mouth in the earthworm, 156. 

 protective resemblances. Resemblances to objects, either animate or 



inanimate, for the purpose of protection; mimicry. 

 proteids. Highly complex compounds of carbon, oxygen, hydrogen, and 



nitrogen and some other elements; the basis of living tissues and a 



necessary part of animal foods, 7, 133. 

 prothallium (Gr. pro = before + thallos = a branch). The small, sexual 



stage of the life history of a fern, 271. 

 protomitomic theory, 50. 

 Protophyta (Gr. protos = first + phyton = plant). The unicellular plants, 



222. 



protoplasm (Gr. protos = first + plasma = substance) . The living sub- 

 stance of organisms, 29, 30, 40, 48. 

 Protozoa (Gr. protos = first + zoon = animal). The unicellular animals, 



92, 222. 



proximal. Nearest to the body. 



pseudonavicellae (Gr. pseudes = false + Lat. navicella = a boat). Spin- 

 dle-shaped spores formed by some Sporozoa as the result of the union 



of cells, 

 pseudopodia (Gr. pseudes = false + pous = foot). Temporary lobes oi 



protoplasm used in locomotion, 52. 



psychology (Gr. psyche = the soul + -logia). The study of mind, 20. 

 pterygoid bones, 180. 



