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In the bell-ffower [Mertensia Virginica) the flowers at 

 different stages are variously colored. The buds are reddish, 

 when the flowers open they are violet; when 

 fertilization has taken place they change to blue. This 

 peculiarity of changing color after fertilization occurs in many 

 flowers like Missouri cnrvAnt (Ribes aureum), cotton [Gossyp- 

 ium herbaceum), horse-chestnut (Aesculus Hippocastanum), 

 buckeye (Aesculus glabra), etc. This change in color, it is 

 thought, is developed to indicate to the insect that its ser- 

 vices are no longer required. Be this as it may^^t is inter- 

 esting to know that color changes do occur. An insect 

 attracted by colors or odors should lose no time after it 

 reaches the flower to get the nectar. Many flowers are 

 therefore characterized by producing certain marks which 

 point toward the nectar, and as some one has said, "These 

 marks are to the insect what the finger-post is to the way- 

 farer, guiding and directing him to his desired destination.'' 

 These marks occur in the form of deeper colored portions of 

 the petals, sepals, etc., lines or hairs on the surface of the 

 corolla, stamens, etc. In the pansy these guides consist of 

 lines that are colored blue or purple. On the rose-colored 

 petals of some flowers there are a number of black rings, 

 lines, etdSiWe must now consider very briefly, nectar. 

 Nectar has bfeen defined by Prof. Trelease as ^J'ftuid always, 

 usually sweet, often odorous, which is elaborated in any part 

 of a plantJ remaining where formed or making its way to 

 some other part; its raison d'etre being the necessity for the 

 removal of some useless or injurious substance, or for some 

 provision to attract nectar-loving animals to the plant for 

 some definite purpose. "Qlt is well known that special parts 

 of the flower or plant elaiBorate nectar; these are commonly 

 called nectar gland8>^ The minute anatomy of these has been 



