PRAIRIE FARMER'S POULTRY BOOK 



The fundamental upon which all breeding rests is repro- 

 duction. 



Reproduction 



Reproduction is the process by which the individual per- 

 petuates its kind. This is accomplished by producing new in- 

 dividuals. There are two kinds of reproduction, known as 

 asexual and sexual. 



Asexual reproduction may occur with the higher forms ot 

 plant life, as in the case of grafting and slipping, where there 

 is no evidence of sex interference. As a rule, asexual repro- 

 duction is found among the lower forms of life. 



Sexual reproduction occurs when one or two sexual cells 

 unite to reproduce a plant or animal. Among plants the sex- 

 ual elements are the spermatazoids and the oospheres. The 

 sexual elements of animals are the spermatazoa and the ova. 

 The varieties of sexual reproduction are conjugation, parthe- 

 nogenesis, and fertilization. 



(a) Conjugation consists in the union of two similar cells. 

 In this method the cells are structurally the same, but as the 

 process is analagous to the sexual method — cytoplasm fusing 

 with cytoplasm, and nucleus with nucleus — it is coiisidered 

 by the best authorities as sexual in character. Examples are 

 found in diatoms and animalcules. 



(b) Parthenogenesis, or unisexual reproduction, is accom- 

 plished by the female. A single sexual cell may be concerned 

 or two cells of the same sex. Illustrations are found in the 

 honey bee, where drones are produced by unfertilized eggs 

 from the queen ; also in the plant louse, whose female may go 

 on producing broods of individuals for ten or more genera- 

 tions without the intervention of the male. Then a male 

 appears, and reproduction by male and female follows. 



(c) Bisexual reproduction, or fertilization, requires both 

 male and female and is illustrated in all species of birds. 

 Birds reproduce by means of an egg, or ovum, which is pro- 

 duced by the female. The egg is really an enlarged cell, being 

 much enlarged to provide room for the storage of nourish- 

 ment. The real center of life in the egg is found on the surface 

 of the yolk and is known as the germinal vesicle. 



Fertilization occurs when the spermatozoon, or sperm cell, 

 fuses with the germinal vesicle. This cannot lake place until 

 after the spermatazoa gain access to the cloaca. This takes 



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