Miscellaneous. 153 



to a great extent, and does not show by accurate observations or 

 experiments that starch is always present in this process, or if it is 

 not present, what substance acts in its place. 



I have assumed the first mode of the production of sugar in ac- 

 counting for the saccharine secretion of the nectary in a little paper, 

 1 De Nectariis, Bonnse, apud Adolphum *Marcum,' 1848, p. 45 seq. 

 I ought there to have demonstrated two things : first, the presence 

 of starch in the nectary, or at least of a substance deposited in it 

 and holding the place of starch ; and, secondly, the existence of a 

 body containing nitrogen, which should act upon the starch or other 

 substance and convert it into sugar. I have endeavoured to demon- 

 strate that such a body containing nitrogen, the formation of which 

 takes place very near the nectary and which operates upon it, is to 

 be found in the pollen and in the ovules, 1. c. p. 35 seq., and p. 48. I 

 shall now proceed in these notes to give additional proofs of the effect 

 of the substances containing nitrogen, which I conclude produce the 

 nectar. In my former work I have ventured the supposition, that 

 the variously-coloured granular substances deposited in the peculiar 

 and globular or nearly globular cells of the nectary are actually 

 starch, or at least hold the place of starch in the process. The 

 presence of starch in the nectary, or the question as to whether the 

 granular matter contained in the nectary be starch or not, is the sub- 

 ject of the following observations. 



It is a well-known fact in chemistry and vegetable physiology, 

 that iodine colours starch blue, and that it is a very delicate test. 

 In answering, therefore, the question as to whether the granular mat- 

 ter of the nectary be starch or not, we shall submit the nectary to the 

 action of iodine. 



In the summer of 1848, I examined the nectaries of upwards of 

 two hundred plants which are indigenous to the county of Norfolk 

 in England. From the effect of iodine on the nectaries of those 

 plants I obtained the following results. But before proceeding, I 

 may be allowed to premise, that the iodine employed for the purpose 

 was dissolved in weak spirits of wine, for I found it the most easy 

 to manage in this form. If the iodine is dissolved in water, its 

 action is not sufficiently rapid. If dissolved in more concentrated 

 spirits of wine, it either colours too darkly, or on the addition of 

 water under the microscope, disturbs the observation by the secretion 

 of crystals. 



The membrane of the cells of the nectary, like membrane in gene- 

 ral, takes a yellow or brown colour, more or less deep, on the appli- 

 cation of iodine. The nectary of Euphorbia Peplus, L., which has 

 naturally a yellow colour, is hardly visibly affected by iodine. In a 

 general way iodine colours the nectary much more deeply yellow or 

 more deeply brown than the other parts of the flower, as the ovary, 

 the style, the petals and sepals. This is the case in Artemisia Absin- 

 thium, L., Lapsana communis, L., Filago germanica, L. (male flower), 

 Bellis perennis, L., Sonchus oleraceus, L., &c. In certain cases, in 

 which there is some doubt as to the true site of the nectary, I would 

 willingly be influenced by the effect of iodine, and assert, that that 

 organ is the nectary which takes the darkest colour on the application 



