76 



SUPEEFLUOUS NECTAE EVAPOEATED IP NOT TAKEN BY 



INSECTS. 



That the nutritive quality of the plants in any growing crop is not 

 diminished by the abstraction of honey from their blossoms would appear 

 to be evident from the fact already referred to, that those plants have 

 actually thrown off the honey from the superfluity of their saccharine juices 

 as a matter which they could no longer assimilate. There would appear, 

 on the other hand, to be good reason to believe that the plants themselves 

 become daily more nutritive during the period of their giving off honey 

 — that is, from the time of flowering to that of ripening their seeds. This 

 is a point upon which, I believe, all agricultural chemists are not quite 

 agreed, but the testimony of Sir H. Davy is very strong in favour of it. 

 In the appendix to his v'ovk already quoted, he gives the results of experi- 

 ments made conjointly by himself and Mr. Sinclair, the gardener to the 

 Duke of Bedford, upon nearly a hundred difierent varieties of grasses and 

 clovers. These were grown carefully in small plots of ground as nearly as 

 possible equal in size and quality ; equal weights of the dried produce of 

 each, cut at different periods, especially at the time of flowering and at 

 that of ripened seeds, were " acted upon by hot water till all their soluble 

 parts were dissolved ; the solution was then evaporated to dryness by a 

 gentle heat in a proper stove, and the matter obtained carefully weighed, 

 and the dry extract, supposed to contain the nutritive matter of the plants, 

 was sent for chemical analysis." Sir H. Davy adds his opinion that this 

 " mode of determining the nutritive power of grasses is sufficiently accurate 

 for all the purposes of agricultural investigation." Further on he reports, 

 " In comparing the compositions of the soluble products afforded by different 

 crops from the same grass, I found, in all the trials I made, the largest 

 quantity of truly nutritive matter in the crop cut when the seed was ripe, 

 and the least bitter extract and saline matter and the most saccharine 

 matter, in proportion to the other ingredients, in the crop cut at the time 

 of flowering." In the instance which he then gives, as an example, the 

 crop cut when the seed had ripened showed 9 per cent, less of sugar, but 

 18 per cent, more of mucilage and what he terms " truly nutritive matter," 

 than the crop cut at the time of flowering. From this it would follow that 

 during the time a plant is in blossom and throwing off a superfluity of saccha- 

 rine matter in the shape of honey the assimilation of true nutritive matter 

 in the plant itself is progressing most favourably. In any case it is clear 

 that the honey, being once exuded, may be taken away by bees or any 

 other insects (as it is evidently intended to be taken) without any injury to 

 the plant, by which it certainly cannot be again taken up, but must be 

 evaporated if left exposed to the sun's heat. 



