Nutrition and Reproduction. 149 



exhilaration, followed as a rule by exhaustion. 

 During, or immediately after, the breeding season, 

 the animal is unfit for food ; every one knows how 

 flabby and tasteless the oyster is during the r-less 

 months; its plumpness and firmness have been 

 sacrificed to the production of life-germs, just as 

 the richness and food value of the salmon, and 

 of all fishes, are sacrificed at that time to the 

 same end. 



Abundant nutriment favors reproduction, as is 

 shown in the case of insects, which, finding abun- 

 dant food, multiply with astonishing rapidity. All 

 other animals are subject to the same law: given 

 abundant food, and the individuals rapidly increase 

 in numbers; diminish the food supply, and there is 

 a corresponding reduction in births, — both within 

 limits. Excessive nutriment, like absolute starva- 

 tion, may prevent reproduction, — the vitality 

 appearing to expend itself in disposing of the 

 unnecessary material. 



While abundant nutriment favors reproduction, 

 lack of nutriment, within limits, hastens the repro- 

 ductive period; that is, the power to live and grow 

 sooner reaches a climax, and dissolution sooner 

 manifests itself in the effort to reproduce. 



Warmth, as favoring nutrition, precipitates the 

 reproductive period ; so that the inhabitants of 

 warm climates mature younger than those of cold 

 climates. 



If, on the other hand, the climate is very cold, 



