THE ORIGIN OF FLOWERS 



191 



regarded as adaptations to flower-visiting, with a few isolated 

 exceptions, of which one will be mentioned later. This is intelligible 

 enough, for the butterfly has nothing more to seek from the flower 

 beyond food for itself ; it does not carry stores for offspring. 



The bees, however, do this, and accordingly we find that in them 

 the adaptations to flower-visiting are not confined to the mouth- 

 parts. 



As far as we can judge now, the flower-visiting bees are 

 descended from insects which resembled the modern burrowing- 

 wasps. Among these the females themselves live on nectar and 

 pollen, and build cells in holes in the ground, and feed their brood. 

 They do not feed them on honey, however, 

 but on animals— on caterpillars, grass- 

 hoppers, and other insects, which they 

 kill by a sting in the abdomen, or often 

 only paralyse, so that the victim is 

 brought into the cells of the nest alive 

 but defenceless, and remains alive until 

 the young larva of the wasp, which 

 emerges from the egg, sets to work to 

 devour it. 



Before I go on to explain the origin 

 of the sucking proboscis of the bee from 

 the biting mouth-parts of the primitive 



, t n i. i • n -i ,i Fig. 48. Mouth-parts of the 



insects 1 must first briefly consider the Cockroach (Periplaneta orientalis), 



after R. Hertwig. la, upper lip 

 or labrum. md, mandibles. 



latter. 



„ ur laurura. ma, manaiDies. mx\ 



Ine biting mouth-parts ol beetles, first maxilla-, with c, cardo, st, 



Neuroptera, and Orthoptera (Fiff. 48), ftipes, Z^ internal lobe or laeinia, 



1 t ' r ^ \ £> ~r /> le, external lobe or galea, and pm, 



Consist of three pairs of jaws, of which the maxillary palp. ?»./'-', the 



l-u .c i. j-i j-v.1 / ' 7\ i labium or second maxilla?, with 



the first, the mandibles (md), are simply similar det aiied parts, 

 powerful pincers for seizing and tearing 



or chewing the food. They have no part in the development of the 

 suctorial apparatus either in bees or in butterflies, so they may be left 

 out of account. The two other pairs of jaws, the first and second 

 maxillas (mx x and mx 2 ), are constructed exactly on the same type, 

 having a jointed basal portion (st) bearing two lobes, an external (le) 

 and an internal (li), and a feeler or palp, usually with several joints, 

 directed outwards from the lobes (pm and pi). The second pair of 

 maxillae (mx 2 ) differs from the first chiefly in this, that the com- 

 ponents of the pair meet in the median line of the body, and fuse 

 more or less to form the so-called ' under lip ' or labium. In the 

 example given, the cockroach (Periplaneta orientally), this fusion 



N 2 



