Knight — 94— Dictionary 



(iv) Telophase. — The chromosomes now take up water 



and become surrounded by a nuclear membrane. Telophase is 



often followed by a short resting stage (interphase). 



2nd Division. 



This is a normal mitosis but with no prophase except when 



an interphase follows telophase. 



Meiotic Division. — Meiosis, q.v. 



Melanic. — Of darker colour. 



Melanism. — Genetically controlled darkening of colour, cf. 

 Industrial Melanism. 



Mendel's Laws. — Mendel enunciated the following basic 

 principles of heredity: (i) That characters exhibit alternative 

 inheritance (dominant and recessive forms) ; (2) that each 

 reproductive cell receives but one member of a pair of de- 

 terminers (genes) existing in the mature individuals; and 

 (5) that the reproductive cells combine at random (J, Here- 

 dity). 



Mendelian Character. — A character the inheritance of which 

 follows Mendel's Laws i.e. one showing allelomorphic inheri- 

 tance. 



Mendelism. — System of heredity based on Mendel's Laws, 

 q.v. 



Menopause. — The period during which the "change of life" 

 occurs in woman. During this period the ovaries atrophy and 

 the oestrus cycle is terminated. 



Mental Ratio. — See under Intelligence Quotient. 



Mericlinal Chimaera. — An incomplete periclinal chimaera; 

 a plant composed of two genetically different tissues one of 

 which partly surrounds the other. 



Meristic Variations. — Differences in the number of parts, 

 segments or organs in the plant or animal body e.g. variations 

 in the number of locules per boll in cotton. 



Merocytes. — The nuclei derived from the supernumerary 

 sperm-nuclei which have failed to conjugate with the ^gg 

 nucleus in cases of physiological polyspermy (Ruckert; Wil- 

 son). 



Merogamy. — A condition in which the gametes are smaller 

 than the vegetative cells, often of different structure, arising 

 by division from the gametocytes (Wilson). 



Merogony. — The development and production of young from 

 a fertilized portion of an ovum containing no female pronucleus. 

 Where the male gamete is of a different species from the 

 female this process is called Bastard Merogony. 



