ALLUREMENTS OF ANIMALS FOR THE DISPERSION OF POLLEN. 



173 



down from the horn-shaped secreting bodies. In Melianthus there are two 

 narrow petals from which the honey drops into the cup-shaped sepal. In Viola 

 each of the two lower stamens is furnished with a long process which projects 

 from the connective, and these processes excrete honey, which trickles down into 

 the expansion of the lower, middle petal surrounding them. In the Toad-flax 

 (Linaria) the honey is excreted by a cushion at the base of the ovary, but flows 

 from it through a narrow cleft between the two longer stamens into the hollow 

 spur of the corolla directed downwards and backwards. 



In addition to portions of the flower proper, bracts can secrete honey. In 

 many flowers single members only are changed into nectaries, but in others a 

 whole whorl of members. Tissue-bodies are often seen which are difficult to 

 explain from the standpoint of speculative morphology, because of the incomplete 

 knowledge of their development, 

 and of which it is impossible to say 

 whether they have arisen directly 

 from the receptacle or from a leaf- 

 structure. On this account it is 

 also not easy to classify or enu- 

 merate nectaries in a thoroughly 

 satisfactory manner. If, therefore, 

 in the following a certain order is 

 observed, this is only for the sake 

 of distinctness, and not with the 



idea that the structures placed side by side belong necessarily to one and the same 

 morphological category. 



In the flowers of most Umbelliferous Plants, of the Cornel, Ivy, Golden Saxi- 

 frage, of numerous species of Saxifrage and Spindle-tree (e.g. Euonymus europoeus, 

 cf. fig. 245 1 ), a cushion of tissue is developed on the ovary. The stamens and 

 floral-leaves stand round this cushion in a circle but not so as to conceal it, and in 

 the open flower within the corolla the honey may be seen glittering in the sun- 

 shine like a thin coat of varnish. The middle of the shallow, basin-shaped flowers 

 of the Sumach (Rhus), of the Buckthorn (Rhamnus), and of the Red Currant 

 (Ribes, cf. fig. 245 2 ) is covered with a fleshy disc which secretes fluid honey over 

 its whole surface. The Box (Buxus) exhibits in the middle of both its staminate 

 and pistillate flowers three little swellings meeting together, each of which deposits 

 a drop of honey. In the Lady's Mantle (Alchemilla), Sibbaldia, and Scleranthus 

 the flower is divided into two stories, into a lower cup-shaped, in which stands the 

 ovary, and an upper, shallower one formed by the floral-leaves. Between the 

 stories is a disc perforated in the middle, or rather a flat ring is interposed which 

 may be compared to the diaphragm in the tube of a microscope. This band also 

 glistens on its upper side in consequence of an extremely thin layer of honey 

 spread over it. The honey-secreting tissue of the Spurge (Euphorbia) is very 

 peculiar. The thickly-crowded flowers are surrounded by a cup-shaped envelope 



Fig. 24&. Honey-secreting tissue in flowers. 



i Flower of the Spindle-tree (Euonymus europceus); x4. a Flower of 

 the Red Currant (Ribes rubrum) cut through longitudinally ; x5. 



