CHAP. XI. IN BELATION TO CROSS-FERTILISATION. 419 



hive-bee more than 2000 years ago, and was noticed 

 by Dobbs in a paper published in 1736 in the Philo- 

 sophical Transactions. It may be observed by any 

 one, both with hive and humble-bees, in every flower- 

 garden; not that the habit is invariably followed. Air. 

 Bennett watched for several hours* many plants of 

 Lamium album, L. purpureum, and another Labiate 

 plant, Nepeta glechoma, all growing mingled togethei 

 on a bank near some hives ; and he found that each 

 bee confined its visits to the same species. The pollen 

 of these three plants differs in colour, so that he was 

 able to test his observations by examining that which 

 adhered to the bodies of the captured bees, and he 

 found one kind on each bee. 



Humble and hive-bees are good botanists, for they 

 know that varieties may differ widely in the colour of 

 their flowers and yet belong to the same species. I 

 have repeatedly seen humble-bees flying straight from 

 a plant of the ordinary red Dictamnus fraxinella to a 

 white variety ; from one to another very differently 

 coloured variety of Delphinium consolida and of 

 Primula veris ; from a dark purple to a bright yellow 

 variety of Viola tricolor; and with two species of 

 Papaver, from one variety to another which differed 

 much in colour; but in this latter case some of the 

 bees flew indifferently to either species, although pass- 

 ing by other genera, and thus acted as if the two spe- 

 cies were merely varieties. H. Miiller also has seen 

 hive-bees flying from flower to flower of Ranunculus 

 lullosus and arvensis, and of Trifolium fragiferum 

 and repens ; and . even from blue hyacinths to blue 

 violets.f 



Some species of Diptera or flies keep to the flowers 



*' Nature,' 1874, June 4th, t ' Bienen Zeitung,' July 1 876 

 p. <J2. p. 183. 



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