434 ANGIOSPERMAE—MONOCOTYLEDONES 



thinner and rather longer, so that the tip of the stigma projects 3 mm. beyond the 

 anthers. It follows that cross-pollination by insect-visits is even more effectually 

 ensured than in L. vernum. Should these fail, automatic self-pollination can take 

 place when the flower closes, the pollen left clinging to the perianth leaves being 

 then pressed against the stigma. 



I looked for the nectary in the same way as in L. vernum, treating the whole 

 of the flower, however, instead of the individual parts, with Fehling's solution, and 

 with the Hoppe-Seyler sugar reagent 0-nitro-phenyl-propionic acid, which precipitates 

 indigo when heated with reducing substances (Zs. physiol. Chemie, vii, p. 83). By 

 treating a number of excised green parts of the plant I had found that each freshly 

 cut surface effects reduction of the reagent and deposits upon it either copper 

 oxide or indigo. When I treated the whole flowers with the reagent I avoided 

 freshly cut surfaces, the exuding juice of which had effected reduction '. I then 

 found that the flowers of L. aestivum showed a deposit of copper oxide and of 

 indigo respectively (when treated with Fehling's solution and the Hoppe-Seyler 

 reagent) only in the middle of the perianth leaves below the green patches on 

 their tips. This was also the case on a smaller scale with the whole style below 



' I have also examined in this way a number of other flowers in which the position of the 

 nectary is doubtful. Entire flowers were soaked in the reagent for twenty-four hours, then heated to 

 the boiling-point, and finally well washed with cold water. The following results were obtained. — 

 (i) Tulipa sylvestrisZ. : the hairs at the bases of the filaments showed a marked deposit of pigment, 

 especially on their inner sides, and the mature stigmatic papillae were covered with indigo. 

 (2) Tulipa Gesneriana L. : the bases of the perianth leaves were permeated by indigo for a distance 

 of about I J cm. ; the tips of the filaments and the stigmatic papillae also turned blue. (3) Orchis 

 latifolia Z. : in flowers treated with the reagents the spurs only became filled with indigo or cuprous 

 oxide respectively : the presence of sugar in the tissues was thus demonstrated. (4) Maianthemum 

 bifolium Schmidt : this only sometimes presented a deep blue colouration of the base of the 

 flower, ovary, and stigma, from which it must be concluded that the secretion of nectar of 

 flowers from the same station is variable. (5) Polygonatum officinale A//. : the tissue in the 

 upper part of the corolla, beneath the green terminal nectar-guides, became deep bine or red 

 from precipitated indigo or cuprous oxide, respectively, indicating the position of the nectar : 

 there was no precipitation in the wall of the ovary. (6) Convallaria majalis Z. : the base of 

 the flower and the perianth showed a rich deposit of colouring matter, proving the presence 

 of sugar-containing tissue. (7) Nymphaea alba Z. : the stigmas of flowers treated with the 

 reagents showed a deposition of colouring matter. (8) Cytisus Laburnum Z. : the swelling 

 surrounding the insertion of the vexillum in front became dark blue from precipitation of indigo 

 after treatment with nitro-phenyl-propionic acid, so that juicy tissue is here present. (9) Vitis 

 vimifera Z. : all the parts of the flower (except the anther-lobes) were strongly charged with 

 colouring matter after treatment with the above-named acid : with Fehling's solution the nectaries 

 became dark and the stigma pale brick-red, while the remaining parts remained colourless. The 

 conclusion may probably be drawn that the nectaries are the chief seat of secretion. (10) Symphori- 

 carpos racemosa Micix. : after treatment with nitro-phenyl-propionic acid all the tissue of the base 

 of the flower, including the hairs, and also the tissue of the ovary surrounding the ovules showed 

 strong precipitation of indigo. This indicates the seat of nectar to be obtained by boring. 

 (11) Solanum Dulcamara Z. : in flowers treated with the reagents there was a strong deposit 

 of colouring matter in the tissue of the flower-base surrounding the ovary, so that the presence 

 of sap in that region must be inferred. (12) Glaux maritima Z. : flowers treated with nitro-phenyl- 

 propionic acid took on a violet tint, which was strongest in the central part of the jierianth leaves, 

 where these adjoin the ovary. The position of sugar-containing tissue is thus indicated. A detailed 

 account of these investigations and the conclusions drawn from them will be found in ' Ober den 

 Nachweis von Nektarien auf chemischem Wege' (Bot. Ccntralbl., Cassel, Ixxvi, 1898). 



