170 



ALLUREMENTS OF ANIMALS FOR THE DISPERSION OF POLLEN. 



edge spring the stamens, and from its outer margin the petals. Between these two 

 floral whorls the fleshy cushion is seen to be beset with clear, diaphanous papillae, 

 which, indeed, secrete no juice, but are nevertheless sucked by small insects visiting 

 the flowers, and are sometimes actually eaten. The same is true of the delicate 

 hairs which beset the staminal filaments of the Pimpernel, Mullein, and Spiderwort 

 (Änagallis, Verhascum, Tradescantia), and which under the microscope appear to 

 be turgid cells arranged singly or in rows just like the hairs which clothe the 

 bottom of the hollow perianth-leaf in the flower of the Lady's-Slipper Orchid 

 (Cypripedium). In several species of the genus Lysimachia (Lysimachia thyrsi- 

 flora, ciliata, &c.), the ovary is covered with small warts whose juicy cells are 

 sucked or devoured by animals; and in the flowers of the Snowflake (Leucojum 



Fig. 244. — Flowers of the Snowflake (^Leucojum vernuin). 



1 Seen from the side. 2 The front part of the flower cut away and the remaining part of the perianth spread out in one 

 plane. Round the style is a cushion of soft tissue which secretes no honey. (Both figures somewhat magnified.) 



vernum; cf. fig. 244), there is a cushion-like mass of cells surrounding the style, 

 whose significance is identical with that of the small warts just mentioned. 

 Numerous Orchids, too, viz. Odontoglossum, Oncidium, and Stanhopea, bear fleshy 

 swellings, pegs, and combs on their perianths which admit of a similar interpreta- 

 tion. 



It also often happens that certain portions of flat petals consist of a cell-tissue 

 which can be easily perforated and sucked by the mouth-apparatus of insects. 

 Such parts are usually distinguished from their surroundings by their greater 

 brilliancy, and one might suppose that this was due to a thin layer of fluid, 

 although this is not really the case. Especially noticeable in this respect are the 

 flowers of Centunculus nninimus, a tiny Primulaceous plant, whose cup-shaped 

 corolla is carpeted at the bottom with slightly-arched, large, juicy, superficial cells, 

 which glitter like silver in the sun. The petals of the Bloodwort (Sanguinaria), 

 of the St. John's Wort {Hypericum), of the Laburnum (Cytisus Laburnum), of 

 Spartium, and of many other plants, behave in the same way. Repeated observa- 

 tions, have also shown that the petals of Hyacinths and of many Anemones, and the 

 flowers of the Centaury {Erythroia), as well as the hollow, honeyless spurs of our 



