172 ALLUREMENTS OF ANIMALS FOR THE DISPERSION OF POLLEN. 



Botacists of earlier time called it nectar, and those parts of the flower which pre- 

 pared and stored it, when they were readily distinguishable, were called nectaries. 



The secretion of honey takes place in many cases through stomata, and these are 

 either distributed uniformly over the surface of the tissue, or collected together in 

 particular spots. Usually the stomata are large and of the form known as water- 

 pores. In the Willows (Salix) the peg-like or tabular nectary bears only a single 

 large water-pore at its truncated end, which pours out colourless honey. There are 

 also nectaries which are quite devoid of stomata and in which the sweet juice comes 

 to light by diffusion through the outer walls of the superficial cells. Sometimes the 

 inner layer of this cell-wall seems to break down into mucilage, becomes changed 

 into a gummy substance, then into sugar, finally pouring out from clefts in the 

 cuticle which has been raised up like a bladder and burst. 



The amount of the honey secreted varies very much. In many plants the 

 drops exuding from the stomata of the petals are so small as to be scarcely visible 

 to the naked eye. In others the honey forms an extremely thin layer, looking as 

 if the tissue had been stroked over with a moist brush. In most cases the small 

 drops flow together into larger drops, which fill the grooves, cylinders, depressions, 

 and cups prepared for their reception. Sometimes these receptacles become filled 

 to overflowing, and then at the least touch the sweet juice flows out of the flowers 

 in drops. This occurs, for example, in Melianthus 'major, growing at the Cape, 

 from whose flowers, with their large cowl-shaped honey-receptacles, an actual rain 

 of honey pours when the inflorescence is shaken. So much fluid honey is secreted 

 by two small horn-like processes in the flower of a tropical Orchid named Cory- 

 anthes, that it continues to flow for a long time from the points of the horns. 

 The lower end of the so-called lip is hollowed out, and gradually the cavity is 

 quite filled by the trickling honey. The quantity of sweet fluid which so collects 

 amounts to about 30 grammes. 



In most instances the most important ingredient of the honey for alluring 

 insects, viz. sugar, is in solution, both on account of its chemical properties and 

 also because the sweet fluid in the hidden grooves and tubes of a flower is thus 

 less exposed to evaporation. Sugar crystals of considerable size formed from the 

 sweet juices of the flower are only found in some Orchids of the genus Aerides. 

 It is not necessary to do more than allude to the fact that, as well as in flowers, 

 the sugary solution which pours out from the bracts of certain Composites becomes 

 changed into crumbly crystalline masses, though it may be deserving of short 

 notice. Of this form of sugar as a much -desired food of ants we shall speak 

 in a subsequent chapter. 



Usually the honey remains exactly where it has been formed and excreted, 

 but there are some flowers in which this is not so; i.e. those where the sweet 

 juice flows from its place of origin and is stored up in special receptacles or 

 honey -bags. This, for example, is the case in the flowers of Coryanthes, Meli- 

 anthus, Viola, and Linaria. It has already been mentioned that in Coryanthes 

 there exists an actual collecting-cup, which receives all the honey as it trickles 



