THEIR REPRODUCTION (EGGS) 295 



order Coraciiformes are white. Taken as a group 

 the Passeriformes present us with the greatest 

 diversity of egg colouration, possibly owing to 

 their high degree of specialisation and the vast 

 variety of conditions under which they live. As 

 a general rule their eggs are more or less spotted, 

 white or blue eggs being exceptional, although 

 characteristic of such families as the Sturnidae, 

 the Dicaeidae, and the Cinclidae. How far the 

 colours of an egg are hereditary we are as yet 

 unable to say. We do know, however, that 

 certain individuals produce certain varieties, and 

 appear to continue to produce them as long as 

 fecundity may last. To what degree the parent 

 transmits certain peculiarities in its own eggs to 

 those produced by its offspring is, however, un- 

 known, although there is some slight evidence 

 to suggest a hereditary tendency. Of course, 

 broadly speaking, in this, as in so many other 

 things in nature, "like produces like," and we 

 know that the eggs of birds continue to exhibit 

 certain general characteristics from generation 

 to generation. Another branch of this subject 

 relates to hybridisation. It has jbeen alleged 

 that the egg containing an hybrid is not exactly 

 similar to that produced by the female, but re- 

 sembles to a greater or lesser extent the eggs of 



