iv EFFECTS OF IMPROVED NUTRITION 103 



In New Zealand the climate is said directly to favour the 

 formation of a longer and stronger wool. 



In more southern regions animals and plants have in 

 general better conditions of nutrition than in the north, and 

 to these also, not alone to the effect of climate, must be 

 attributed the changes of form which they undergo when 

 transferred from north to south. Of the importance of the 

 influence of nutrition on growth and change of form I have 

 already spoken. 1 



I have only to add here that the increase in size of animals 

 of the same genus, and even of the same species, in passing 

 from north to south is sometimes in the highest degree 

 conspicuous. It is often then most clearly evident that where 

 this increase in size has been accompanied by the develop- 

 ment of other characters, the formation of new species has 

 become possible, and it is often a debated question in such 

 cases whether the changed forms are to be called new species 

 or not. I may mention in illustration the species of the 

 genus Scorpio, which in its smallest form as Scorpio germanus 

 occurs as far north as the Tyrol. I may mention further the 

 wonderful increase in size of the species of Julus and Scolo- 

 pendra towards the Equator. 



I have minutely investigated and described an example of 

 such increase in size and change in colour, and of the char- 

 acters connected with these by correlation, in the common 

 lizard (compare below). 



The acquired and inherited characters depending on nutri- 

 tion in our domestic animals are so well known and so obvious 

 that nothing further need be said about them. 



A little careful consideration, however, will also show that 

 a large number of these characters must have arisen without 



1 With reference to the effect of nutrition in the modification of forms, compare 

 especially what is said below on bees as an example of the importance of acquired 

 and inherited characters. 



