442 APPENDIX 



KATABOLISM. The destructive phase of metabolism. See Anabo- 



lism. 



KINETIC ENERGY. Energy possessed by virtue of motion. E.g., 

 union of C with 2 transforms chemical potential energy into 

 kinetic energy, i.e., heat, etc. See Potential Energy. 



LAMINA. The blade of a leaf. 



LARVA. An immature stage in the life history of certain animals, 

 usually active arid differing widely in appearance from the adult. 

 E.g., caterpillar of a Butterfly, tadpole of Frog. 



LENTICELS. Openings on the outer surface of the bark which per- 

 mit a slight amount of gaseous interchange. Arise as stomata in 

 the young shoot. 



LININ. The material of the reticulum of the nucleus, upon and 

 through which the chromatin appears to be distributed in the 

 resting cell. The representative within the nucleus of the gen- 

 eral cytoplasmic reticulum. 



LINKAGE. Tendency for certain characters to be inherited in 

 groups, probably because the genes for the characters are closely 

 associated on the same chromosome. 



LYMPH. Essentially plasma and white blood corpuscles which have 

 passed through the capillary walls to supply the milieu of the 

 tissue cells. 



MACRONUCLEUS. The large 'vegetative' nucleus in Infusoria with 

 dimorphic nuclei; e.g., in Paramecium. See Micronucleus. 



MANDIBLES. Jaws. The third pair of appendages of the head of 

 the Crayfish. 



MATURATION. Final stages in the formation of the germ cells, in- 

 volving chromosome reduction. 



MAXILLIPEDS. The three posterior pairs of appendages of the 

 head of the Crayfish. 



MECHANISM. The doctrine that the phenomena of life are inter- 

 pretable in terms of the laws of matter and energy which hold 

 in the realm of the non-living. See Vitalism. 



MEDUSA. Sexual, gonad-bearing generation of hydra-like animals, 

 the Hydroids. 



MEGASPORANGIUM. A sporangium which bears megaspores. 



