158 AUSTRALASIAN BEE MANUAL 



(silex, lime, aluminium, etc.), which take away from 

 the soil those substances that are required to be returned 

 to it in the shape of manures. The saccharine matter, 

 once it is secreted by the plant and separated from it, 

 is even useless as a manure. Liebig says on this head, 

 page 21,— 



The most important function in the life of plants, or, in 

 other words, in their assimilation of carbon, is the separation 

 — we might almost say the generation — of oxyg'en. No 

 matter can be considered as nutritious or as necessary to 

 the growth of plants which possesses a composition either 

 similar to or identical with theirs, because the assimilation 

 of such a substance could be effected without the exercise 

 of this function. The reverse is the case in ^the nutrition 

 of animals. Hence such substances as sugar, starch, and 

 gum, themselves the products of plants, cannot be adapted 

 for assimilation ; and this is rendered certain by the experi- 

 ments of vegetable physiologists, who have shown that 

 aqueous solutions of these bodies are imbibed by the roots 

 of plants and carried to all parts of their structure, but are 

 not assimilated ; they cannot, therefore, be employed in 

 their nutrition. 



NECTAK OF PLANTS INTENDED TO ATTRACT INSECTS. 



The secretion of saccharine matter in the nectaries 

 of flowers is shown to be one of the normal functions 

 of the plant, taking place at the season when it is 

 desirable to attract the visits of insects for the purposes 

 of its fertilisation. It may, then, be fairly asserted that 

 the insect, when it carries off the honey from any 

 blossom it has visited, is merely taking with it the fee 

 or reward provided by nature for that special service. 



SOMETIMES THROWN OFF AS SUPERFLUOUS. 



There are, however, occasions when considerable 

 quantities of such matter are thrown off or exuded by 

 the leaves, which effect is taken to indicate an abnormal 

 or unhealthy condition of the plant. At pages 106 and 

 107 of Liebig'.s book (speaking of an experiment made 

 to induce the rising sap of a maple-tree to dissolve raw 



