78 NATURAL HISTORY. [CH. IV 



Sometimes a series of intersecting" arcades per 

 mitted free egress to the bees, but refused admit- 

 tance to their enemies. These fortifications were 

 massy and their substance firm and compact, being 

 composed of propolis and wax." 



When the entrance of their hives is itself re- 

 stricted, or care is taken to contract it soon enough 

 to prevent the devastation of their enemies, bees 

 dispense with walling themselves in. Here, then, 

 we have the invention and adaptation of means to 

 a proposed end. 



Nothing is more calculated to convince us that 

 animals are not mere machines, than seeing them 

 varying their proceedings according to circum- 

 stances. Even their mistakes and irregularities 

 cause us to doubt the doctrine, that all their actions 

 are the result of organization. Of this, bees furnish 

 abundant instances. 



"The geometrical regularity with which the 

 labours of bees are conducted," observes Bonnet, 

 "has been justly celebrated ; it requires, however, 

 but little observation to perceive much variety in 

 the construction of the cells and this is some- 

 times so remarkable as to strike the most careless 

 observer. Some of them are circular, and some 

 elliptical, instead of the usual hexagonal form. 

 The bottoms of the cells show also considerable 

 irregularities. It often happens, that instead of 

 being constructed in the usual manner, of three 

 lozenge-shaped pieces, they are formed of four, five, 

 or six pieces, of a shape more or less irregular, but 

 which approach a quadrilateral form or square, more 

 nearly than any other figure. The dimensions of 

 the common cells are still more various than their 

 opening or their base. The cells are usually about 

 five lines* in depth; but I have seen some more than 

 eighteen lines deep. These unusually long cells 



* A line is the twelfth part of an incU, 



