igo THE FIRST PRINCIPLES OF HEREDITY 



Maturation (L. maturus, ripe) (p. 36). 



Mean (L. medianus, middle) (p. 150). 



Median (L. medianus, middle) (p. 150). 



Mendelism, Mendelian, the theory of Mendel (p. 120). 



Mendelize, to conform to the Mendelian law (p. 140). 



Mesoderm (Gr. mesos, middle; derma, skin), the middle germinal 



layer of the embryo (p. 48). 

 Metabolism (Gr. metabole, a change), the sum of the chemical 



changes within the living organism. 

 Metaphyta (Gr. meta, after ; phyton, plant), many-celled plants 



(p. 6). 

 Metazoa (Gr. meta, after ; zoon, animals), many-celled animals 



(p. 6). 



Microsome (Gr. mikros, little ; soma, body) (p. 58). 

 Mid-parent (p. 162). 

 Mitosis (Gr. mitos, a thread) (p. 30). 

 Mnemic (Gr. mneme, memory), pertaining to memory. 

 Mode (L. modus, rule), (p. 150). 

 Modification (L. modus, a measure ; facere, to make), changed 



condition. 



Monoecious (Gr. monos, single; oikos, house), having the two sex- 

 organs upon the same individual (p. 22). 

 Monohybrid (Gr. monos, single, and hybrid) (p. 127). 

 Monotremata (Gr. monos, single; trema, hole), the lowest order ol 



mammals having a single external opening for the genital and 



digestive organs. 

 Morphological (Gr. morphe, form; logos, discourse), pertaining to 



the science of form. 



Morphoplasm (Gr. morphe, form ; plasma, form) (p. 57). 

 Morula (L. morum, mulberry) (p. 47). 

 Mucous (L. mucus, slime), slimy, pertaining to the internal lining 



of the mouth, etc., which secretes a slimy substance. 

 Multi-cellular (L. multus, many; cellula, cell), many-celled. 

 Mutation (L. mutare, to change) (p. 140). 

 Myranida (Gr. myrios, numberless), a marine worm. 



Neurosis, neurotic (Gr. neuron, a nerve), a nervous disease. 

 Nucleus (L. nux, nut), kernel (p. 5). 

 NucleolUS (L.), a small kernel (p. 30). 



Ontogenesis, ontogenetic (Gr. on, ont-, being; genesis, generation), 



the individual development of an organism. 

 Ovum (L.), egg. 



