xii INTRODUCTION 



the two ends placed one in the palm of each hand, the 

 fingers may be closed and any amount of pressure brought 

 to bear upon it, and it cannot be broken, provided it is 

 fairly pressed from end to end. Again, eggs may be thrown 

 about in a grass field like balls without breaking, unless one 

 of them happens to fall upon the sharp edge of a stone. 

 Many amusing illustrations of this fact have occurred to 

 the writer. On one occasion he was accused of relating 

 a falsehood by stating that eggs from a wild duck's nest 

 had been thrown by himself from a boat on to the bank, 

 and that they had been reclaimed without being injured. 

 The accusation was disproved by a large number of hen's 

 eggs being thrown out of the College window on to the 

 lawn, the accuser undertaking to pay for those not broken, 

 which involved the purchase of the whole basket. It may 

 be asked, if the shell is so strong, how is it possible that 

 the delicate chick in the interior can emerge when arrived 

 at maturity? This question is usually ignorantly and errone- 

 ously answered by its being stated that the hen chips the 

 shell to allow the escape of the chicken. No assistance 

 of the kind is required, if it were it is evident that 

 chickens would never emerge in an incubator. Shortly 

 before the period of hatching, the regular structure of the 

 shell, which is built up with extraordinary perfection, breaks 

 down, and the shell becomes what may be called dis- 

 integrated or almost rotten, so soft as to enable the 

 enclosed bird to cut its way through the shell by repeated 

 blows with the little sharp-pointed, hard egg-tooth which is 

 on the tip of the beak, and which falls off after the bird has 

 been hatched a few hours. The existence of this contrivance 

 is not generally recognised, and the writer had much pleasure 

 in furnishing Sir William Flower with specimens illustrating 



