1^4 ON THE NECTARIES OF FLOWERS. 



ciifFerent plants at that time, when even the stalk, as well as the 

 axilla of the leaves, is reddened by its tint. I took out, there- 

 fore, the whole cylinder belonging to the line of life, and pro- 

 cured a drop or two of this luscious liquid. I then divided the 

 wood from the same plant, and by pressure obtained a little 

 sap : and the mixture of the two immediately changed the co- 

 lour of the liquids, and converted the light green of the sap to 

 a dark red colour. That the sap running in the perfect wood is 

 Effect of the almost always a pretty powerful alkali, I have long been con- 



acid and alkali yinced (differing from that found in the alburnum -•) and that 

 >n colouring ,, , , , , ., , -, 



plants. t"S buds, on the contrary, are more or less acid, may be easily 



shown by cutting and then immersing them in a weak alkaline 

 liquor. The direct change of colour produced in the wood by 

 passing a feeble electric stroke through a plant also proves it, 

 since it reddens the wood vessels, but has no such effect on the 

 buds. We may therefore, I think, conclude, that the redden- 

 ing of the stalk is caused by the bleeding of the line of life, and 

 the mixture of the acid and alkali in the bosom of the leaf: 

 and we may also look to the nectary for three of the most 

 powerful effects observable in the life of a plant. 



I now turn to the third division of my subject, and shall 

 show the various species of nectary found in plants, both con- 

 cealed and open. I need not here represent the manner in 

 which I dissect flowers, as my former letter has shown it, and 

 proved, I hope, how impossible it is, that after cutting them in 

 three different directions, I should be mistaken in the formation 

 of their various parts 5 since in such a display they would mu- 

 tually be the means of detecting each other, if not critically 

 exact in their delineations. All flowers, with respect to the 

 situation of their seed vessels, may be divided into three distinct 

 kinds: those which have their seed-vessels above the flower ; 

 those in which the same part is found much below, and those 

 in which the germe occupies nearly the centre. In the first and 

 second the secret nectary is generally found in a deep cavity 

 either above or below the seed-vessel, according to its situation 

 in the flower ; but in the last it is so various, that there is no 

 The situation giving rules to find it. In a monopetalous corolla the secret 

 of the secret nectary generally forms a little box under the seed-vessel, which 

 nectary in mo- , . , ... ^ ■ , r ■>■ 



nopctaious has sometimes the stamen opening into it, and is therefore dis- 



'jlants, covered by drawing out the filaments, and finding their ends 



2 steeped 



