854 OUTLINES OF EVOLUTIONARY BIOLOGY 



countries where they are plentiful this is perhaps the case. 

 They visit the flowers in order to collect both honey and pollen, 

 to be used as food for themselves and their offspring. The honey 

 is usually found at the bottom of a long narrow tube formed by 



the lower part of the corolla, 

 so that in order to reach it 

 the bee requires a corre- 

 spondingly long and narrow 

 instrument. This is pro- 

 vided in the si i ape of a very 

 complicated proboscis (Fig. 

 179), formed by modifica- 

 tion, especially elongation, 

 of certain of the appendages 

 surrounding the mouth, 

 which in more primitive 

 insects, like the cockroach, 

 remain short and simple. 

 When not in use the pro- 

 boscis is neatly folded away 

 beneath the head, but when 

 a flower is visited it is un- 

 folded and inserted into the 

 tube containing the honey, 

 which is then drawn up into 

 the bee's stomach by means 



FIG. 179. Head of a Bee, showing thecom- 



of a special sacking ap- 



plex Proboscis formed from" modified paratus. In butterflies and 

 Mouth Parts. (From Weismann's moths also a somewhat 

 " Evolution Theory.") 



at, antennae; Au, large compound 

 ocellus ; la., labrum or upper lip ; 



3; au, 

 , outer 



division of second maxilla (paraglossa) ; Zi, 

 ligule or tongue, formed by fusion of inner 

 divisions of second maxillae ; md, mandible ; 

 mx l , mx\ first and second maxillae ; pi, 

 labial palp; p:m., maxillary palp'. 



similar proboscis is used for 

 the same purpose, but it 

 differs so much from that of 

 the bee in details of struc- 

 ture as to indicate that it has 

 been independently evolved 

 from the primitive mouth parts of some remote insect ancestor. 

 In both cases the mouth appendages have become specially adapted 

 for the very special purpose of sucking honey, ai:d the necessity 

 for the fulfilment of the same function has led, as usual, to a 

 superficial resemblance between the two types of proboscis. We 

 have here, of course, another illustration of convergent evolution. 



