314 DOMESTICATED ANIMALS AND PLANTS 
Grading. Breeding scrub or unpedigreed stock to registered males. 
Heredity. The transmission of racial characters from ancestry to offspring. 
Hybrid. The offspring of hybridization, carrying the blood of two or more 
species or races. 
Hybridizing. That kind of crossing in which the male and female are of 
different species or of distinctly different races. 
Id. A term used by Weismann to denote an orderly and definite association 
of biopheres operating together towards the determination of a definite 
character. 
Latent characters. See Characters, latent. 
Mammals. Certain species of higher animals in which the fertilized ovum is 
retained and embryonic development takes place inside the body of the mother 
until birth ; specifically, those species which suckle the young. 
Maturation. The final stages of division in sex cells just before attaining the 
conditions suitable for fertilization. 
Mean. The average. 
Mendel’s law. The law which states the way in which racial characters will 
be distributed among the offspring of hybrid parents. 
Methodical selection. The imitation by man of the operation of natural selec- 
tion as he attempts to secure the favorable development of especially desirable 
characters in domesticated animals and plants. 
Mimicry. The resemblance of one species to another or to some natural 
object in such a way as to be protective against possible enemies. 
Mitosis. The process of cell division in ordinary growth. See also 
Maturation. 
Mode. The most common or typical value of a racial character. ; 
Mutant. An individual or strain essentially new and produced spontaneously 
by nature through crossing, bud variation, or otherwise; synonymous with the 
older term “ sport.” 
Mutation. The production of mutants or sports, which see. 
Natural selection. The oppressive effect of the environment by which many 
individuals are unable to endure, and which therefore operates to destroy a 
large proportion of the race. Those which are able to endure the hard fea- 
tures of the environment not only survive, but, prospering by other conditions, 
are said to be se/ected in this natural way. 
Nucleus. That part of the cell which contains the chromosomes, which 
takes the lead in cell division, and which seems normally to be equally divided 
between the daughter cells, whether in ordinary growth or in maturation. 
Ovary. The organ in which the ova or female reproductive cells develop. 
Oviporous. Said of species which lay eggs in which, like birds, the em- 
bryonic development takes place outside the body of the mother by the 
process of hatching. 
Ovule. The female sex cell of the higher plants, which, upon fertilization by 
the pollen cell, is capable of developing into a new plant. 
