Pagina (328/607)



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      A Chiavari, a Genova, a Firenze, a Vallombrosa, a Bologna sorpresi sui nettarii delle veccie formiche e sempre formiche, non mai né api, né bombi, né altri imenotteri.
      Sui nettarii stipolari delle veccie si è portata anche l’attenzione di CARLO DARWIN come si evince dal seguente passo estratto dalla sua opera: "Cross and self fertilization in the vegetable Kingdom, 1876, pp. 402, 403". There are a considerable number of plants which bear small glands on their leaves, petioles, phyllodia, stipules, bracteae, or flower peduncles, or on the outside of their calyx, and these glands secrete minute drops of a sweet fluid, which is eagerly sought by sugar-loving insects, such as ants, hive-bees and wasps. In the case of the glands on the stipules of Vicia sativa, the excretion manifestly depends on change in the sap, consequent on the sun shining brightly; for I repeatedly observed that as soon as the sun was hidden behind clouds the secretion ceased, and the hive-bees left the field; but as soon as the sun broke out again, their returned to their feast". E aggiunge in calce la seguente nota. "I published a brief notice of this case in the ‘Gard. Chronicle’ 1850, July 21, p. 487, and afterwards made further observations. Besides the hive-bee, another species of bee, a moth, ants, and two kinds of flies sucked the drops of fluid on the stipules. The larger drops tested sweat. The hive-bees never even looked at the flowers which were open at the same time; whilst two species of humble-bees neglected the stipules and visited only the flowers".

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Memorie di biologia vegetale
di Federico Delfino
pagine 607


Chiavari Genova Firenze Vallombrosa Bologna Kingdom Vicia Gard July