viii CONTENTS. 



PAGE 



doptera and on Molluscs Characters of maritime plants 

 probably due to saline environment Conversion of A. 

 salina into A. milJiausenii and into Branchipus Effect of 

 increased salinity on characters of the cockle Influence of 

 salinity on rate of growth of Tubularians, and on size of 

 sea-urchin larvse, 260 



CHAPTER IX. 



THE EFFECT OF FOOD AND OF PRODUCTS OF 

 METABOLISM. 



Effect of artificial manures on growth of crops Effect of 

 nutrition on plant variation Development of bees and 

 of aphides in relation to food Influence of nature of food 

 on wing markings of certain Lepidoptera Dependence of 

 colour of larvae on plant pigments Influence of food on 

 growth of tadpoles Plumage of certain birds altered 

 by abnormal diet Quality of food influences organs of 

 digestion Every organism probably has specific metab- 

 olism, which has especially adverse action on its own 

 growth Products of metabolism may stimulate growth- 

 Effects of small quantities of urea, uric acid, and ammonium 

 salts Influence of volume and of surface area of water on 

 growth of pond snail Influence of surface area on growth 

 of tadpole Effects of increasing quantities of metabolic 

 products on characters of a snail, and of a Crustacean, . 281 



CHAPTER X. 

 THE EFFECTS OF CONDITIONS OF LIFE IN GENERAL. 



Local conditions of life perhaps the cause of local races, but 

 proof of this as a rule impossible American and European 

 trees compared Alpine and Arctic plants Effects of 

 cultivation Local races of oysters and of snails Lepi- 

 doptera in Malay Archipelago Local races of shrimps, of 

 mackerel, and of herring North American birds and 

 mammals Action of climate on goats and on rabbits 

 Effect of domestication on rabbits, pigeons, fowls, and 

 ducks, 310 



