156 



INTRODUCTION 



hair, which may even spoil the flavour of the nectar next tasted. But by examining 

 the hgula of a highly specialized bee under a high power of the microscope, a special 

 arrangement by which this imperfection is obviated will easily be recognized. In less 

 specialized bees the whole length of the tongue is supported by a massive chitinous 

 rod ; but in more specialized bees this rod is converted into a capillary tube, which 

 opens into the hollow of the spoon-shaped lappet at the tip of the ligula. As soon as 

 this ' spoon ' is immersed in nectar, part of it rises in the capillary tube to the base 

 of the ligula and to the taste-organs. Should the nectar, when tasted, prove 

 disagreeable to the bee, it need not even begin to suck, and can easily expel the 

 minute quantity of liquid that fills the tube.' (Cf. O. J. B. Wolf, ' Das Riechorgan 

 der Biene,' 1874.) 



Fig. 67 represents the head of a humble-bee in the suctorial position, with 

 the proboscis half extended. If now, from this position, the base of the ligula is 



Fig. 67. Head 0/ Botnbiis horlotitin, L, 9, 'with proboscis half extended ; seeti from the side 

 rafter Herm. Mttller). (X 7.) References as in Fig. 66. 



retracted into the hollow end of the mentum (as shown in Fig. 68), its end {utju) 

 is drawn back saturated with nectar into the suctorial tube. If the cardines 

 (Fig. 67, c), now turned vertically downwards, are rotated backwards, the base of 

 the suctorial tube (at pni) will be drawn back to the opening of the mouth (between 

 the labrum and the bases of the mandibles, and by a simultaneous sucking action 

 of the sides of the body, and pressure of the erectile whorls of hair, the nectar is 

 quickly carried from the tip of the ligula into the mouth '. 



* Hermann Muller thinks he can conclude with certainty that the whorls of hair have the 

 function described above from experiments he made on chloroformed bees and humble-bees. In 

 these, sometimes, if the tip of the ligula was dipped in syrup before complete loss of consciousness, 

 the suctorial movements were induced so slowly that their separate stages could be clearly dis- 

 tinguished. They were as described above. What went on between the chitinous plates of the 

 laciniae and labial palps was of course invisible, but when these parts were drawn aside, after the tip 

 of the ligula had been moistened with syrup, a successive erection of the whorls from the tip to the 

 base could sometimes be clearly seen. The fact that the basal part of the ligula, which is retracted 

 into the hollow of the mentum, is free from whorls of hair is in accordance with this interpretation. 

 [But in the English translation of Miiller's book (p. 6 1), which incorporates more recent observations of 



