RANUNCULACEAE 



5i 



Kronfeld states that Handlirsch observed eight species of humble-bee in lower 

 Austria, and Hoffer ten in upper Austria, those with a short proboscis (B. mastru- 

 catus, B. terrester, B. soroensis, and B. mendax) obtaining the nectar by perforating 

 the flowers. 



102. A. variegatum L. 



Visitors. Kronfeld in Austria saw Bombus agrorum ($J and $) and B. 

 hortorum ($, 5, and J) sucking legitimately, also Halictus morio and other short- 

 tongued insects vainly seeking for nectar. Schulz observed perforated flowers of 

 this species in Thuringia. 



103. A. Lycoctonum L. (Sprengel, 'Entd. Geh.,' p. 279; Herm. Muller, 

 'Alpenblumen/pp. 139-40; MacLeod, * Pyreneenbl.' ; Aurivillius, C, 't)ber d. Bl. 

 u. Befrucht. v. Aconitum Lycoctonum L.,' Bot. Centralbl., Cassel, xxix, 1887, 

 pp. 1 25-8; Kronfeld, ' Uber d. biol.Verhaltn. 



d. Aconitumbliite,' Bot. Jahrb., Leipzig, xi, 

 1889; Loew, ' Blumenbesuch,' I, p. 28; 

 Knuth, ' Bliitenbesucher '). This agrees 

 essentially with the species already de- 

 scribed in the structure of its flowers, but 

 the nectar is so deeply placed as to be 

 only accessible to humble-bees with a very 

 long proboscis. The upper sepal of the 

 yellow blossom is an almost vertical cylinder, 

 which serves as a protective envelope for 

 the nectaries. Each of these is produced 

 into a spiral tube (of one and a half turns), 

 which is full of nectar, that is here secreted 

 very abundantly. The stalk of the nectary 

 is about 20 mm. long, and a proboscis 

 of about the same length is necessary for 

 sucking, as humble-bees can get no foot- 

 hold in the cylindrical sepal, but are obliged 

 to cling to the stamens and carpels. 



Visitors. In Central and North Germany the yellow monkshood is visited 

 exclusively by Bombus hortorum L. ; in the Alps almost solely by B. opulentus 

 Gerst. (=B. Gerstackeri Mor) 1 . These two humble-bees have a longer proboscis 



Fig. 20. Aconitum Lycoctonum, L. (after Herm. 

 Muller). A. Flower in the second (female) condi- 

 tion ; seen from the side. Natural size. B. Longi- 

 tudinal section of the same (nearly twice natural 

 size). The upper stamens have already fallen off. 



1 Frey-Gessner CFxkursionen im Sommer 1880,' Mitt. Schweiz. Ent. Ges., vi, 1881) first pointed 

 out that the old o of Bombus Gerstackeri Mor. consistently alights upon Aconitum Lycoctonum ., the 

 (jj and 5 upon A. Napellus Z., and this phenomenon has been described by Dalla Torre as hetero- 

 tropky (cf. vol. I, pp. 1601). This investigator explains the adaptation as due to the extremely short 

 working period of this humble-bee, which only appears in July, and of course disappears at the end 

 of September or beginning of October, and to the fact that ^ and J appear simultaneously with 

 the foundress-queens (from Aug. 20 on), so that it is in the interest of the species that they should 

 visit different flowers. The term ' heterotrophy ' {trtpos, different ; rpcxprj, food) is reasonable in so 

 far that in districts where A. Lycoctonum and A. Napellus occur side by side in great profusion, the 

 <j> of B. Gerstackeri appears actually only to visit A. Lycoctonum, the |jf and i on the other hand only 



E 2 



