47 



CONDITIONS OF REPRODUCTION. 

 What are the conditions of reproduction? They are five, and 

 they are as follows: 



1. Maturity. The animal, bird or plant must be in the inter- 

 mediate state between growth and decay. The desire for repro- 

 duction is greater at the beginning of this intermediate state, and 

 steadily declines towards its end. This is why a fowl will lay 

 more eggs the first year after coming to maturity than in any 

 subsequent year of her life. 



2. Vitality. Reproduction draws upon the vital forces as 

 does no other act. This is why the bird feels a desire to incubate 

 .after her litter is completed she needs rest. The broody hen 

 should be treated with great consideration, and not ruthlessly 

 abused, as is too often the case. The immediate effect of disease 

 or injury is to weaken the desire for reproduction. A sick hen is 

 not a laying hen. 



3. Nutrition. The animal, bird or plant must be well fed. 

 Darwin makes nutrition the principal factor in reproduction. He 

 says: "With hardly an exception our domesticated animals, 

 which have long been habituated to a regular and copious supply 

 of food, without the labor of searching for it, are more fertile 

 than the corresponding wild animals. The amount of food affects 

 the fertility of even the same individual ; thus sheep, which on 

 mountains never produce more than one lamb to a birth, when 

 brought down to lowland pastures, frequently bear twins. As 

 Mr. Dixon has remarked, "High feeding, care and moderate 

 warmth induce a habit of profligacy which becomes in some 

 measure hereditary." (Animals and Plants Under Domestica- 

 tion, vol. ii, chap, xvi.) 



4. Sanitation. Sanitation profoundly affects vitality, and 

 without sanitation the other conditions cannot produce their full 

 effect. The hen house should be kept perfectly clean, the birds 

 free from parasites ; they should not be crowded, and should be 

 supplied with everything necessary to comfort and health. 



5. Sex. In the very lowest forms of life reproduction is 

 asexual that is, the new life is produced not by the coming 

 together of male and female, but by fission or cleavage from the 

 parent organism. But all higher animals and plants are repre- 

 sented by distinct male and female forms, and the more com- 

 pletely each form is sexed the greater its power of reproducing its 

 kind. 



