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NOTES AND MEMOEANDA. 



Researches on the Proboscis of Butterflies. — W. Breitenbach 

 has undertaken a series of observations * on the hairs with which the 

 proboscis of butterflies is covered, and on the relation of these to the 

 curious " Cylindergebikle " or sheathed hairs by means of which many 

 Lepidoptera are enabled to pierce the tissues of plants for the purpose 

 of getting at the contained juices. 



The ordinary typical hairs consist of a basal portion or cylinder 

 composed of a dark chitinous material, and either partly imbedded 

 in the substance of the proboscis or projecting freely from its siu*- 

 face, and of the hair projier, the proximal portion of which is im- 

 bedded in the cylinder, while the distal, usually by far the larger 

 part, is free. In Zygcena JiUpendulce the hairs on the greater part of 

 the proboscis have the ordinary characters, but, near the free end 

 of the organ, the edge of the cylinder is jiroduced into four eleva- 

 tions, placed at equal distances from one another ; the cylinder itself, 

 moreover, is proportionally longer and the hair proper proportionally 

 smaller than in the typical hair. In Pieris a similar structure ob- 

 tains, but the cylinder is strengthened by longitudinal bands, one 

 for each of the five points into which its edge is produced, and of a 

 darker colour and firmer consistency than the rest of the cylinder. 

 In Epinephele Janira, the size of the whole apparatus is greatly 

 increased, the processes on the edge of the cylinder have become 

 actual teeth, and the hair proper is so much reduced as to form a mere 

 papilla just overtopping the circlet of teeth. A structure is thus 

 produced eminently fitted for piercing the tissues of plants. A further 

 modification occurs in Arge Galathea, in which, besides the row of 

 teeth round the edge of the cylinder, there are three other circlets, 

 encompassing, at equal intervals, its lateral surface : each of the four 

 circlets is six-toothed. In Catocala hymencea the structure seems at 

 first sight to be altogether different : the cylinder is provided with six 

 vertical plates standing out from its lateral surface, and projecting over 

 its edge in the form of sharp points : these plates may be considered 

 as having been formed by the coalescence of superposed rows of teeth, 

 such as exist in Arge. 



From these observations it seems highly probable that the sheathed 

 hairs have been developed from ordinary hairs by the gradual dimi- 

 nution of the hair proper, especially of its extra-cylindrical portion, 

 and by the simultaneous increase in size and strength of the sur- 

 rounding cylinder. The advantage accruing to the insect from the 

 change is obvious ; with a proboscis provided merely with ordinary 

 hairs it would be able to take advantage only of free nectar, that is 

 juice actually poured out by the secreting glands of the plant, whereas 

 with the sheathed hairs it would be able to pierce the cell-walls and 

 derive an additional quantity of nutriment by drawing upon the in- 

 ternal juices. This view is supported by the fact that Lepidoptera 

 visit flowers which produce no free nectar. 



* ' Aichiv f. Mik. Anat.,' vol. xv. p. 8. 



