APPENDIX 2 



213 



mammals are die only homoiothcrmal animals — all others are poikilo- 

 thcrmal. 

 Hormone. A chemical messenger: a substance secreted by one organ that 



affects another after transport by way of the circulation. 

 Host, Dehnitive. In parasitology, the host that harbours the adult parasite. 

 Inlier. Patch of a geological formation lying on an area of another. 

 Inversion. A meteorological condition in which the air becomes warmer as 



the altitude increases, instead of cooler, as is usually the case. 

 IsoPHENE. Line joining points of equal date. 

 Joint Function. A statistical relation in which two or more independent 



variables interact so that the combined effect is different from the sum of the 



separate effects. 

 Kinesis. Random movement in response to a stimulus. 

 Larva. A free-Hving stage of a young animal that differs, often very markedly, 



from the adult. 

 Metamorphosis. The change from tadpole into frog. 

 Metazoa. Multicellular animals. 



Metacercaria. a stage in the hfe history of a trematode. 

 MiCROPHAGY. Feeding on microscopic food. 

 Multiple Correlation Coefficient. A correlation coefficient that expresses 



the closeness of the relation between a dependent variable and two or more 



independent variables. 

 Neotenic. An animal that attains reproductive maturity without having adult 



form. 

 NoTOCHORD. A rod of cartilage that in the lower vertebrates and also in 



tadpoles serves the same function as the backbone. 

 Oestrus. The sexual stage of a female animal. 

 Oesophagus. Gullet. 



Olfactory. Concerning the sense of smell. 

 Oligotrophic. An oHgotrophic pond is one that has relatively Httle nutriment 



in it, and consequently relatively Httle life. Animals and plants that do occur 



are often specially adapted for the Hfe there. Contrasts with "eutrophic." 



Frog ponds are usually, perhaps always, eutrophic. 

 Operculum. Gill cover. 

 Orographical. Attribute to altitude. 

 Ovisac. The dilated part of the oviduct, where the eggs are stored between 



ovulation and oviposition. 

 OviPOSiTiON. The laying of eggs. 

 Ovulation. The discharge of vitelH from the ovary. 

 Pathogen. Agent of disease. 

 Peristaltic. Having a contractile motion in wave-Hke form that moves food 



along the alimentary canal. 



