On the examination of a hybrid digitalis / by J.S. Henslow.

  • John Stevens Henslow
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: On the examination of a hybrid digitalis / by J.S. Henslow. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    Flowers of lutea are not unfrequent with the lower lip notched (Fig. 7), which indicates the presence of a supernumerary petal blended into the tube of the corolla. In about half a dozen instances I even found this petal quite free, (Fig. /3) and I be- lieve occupying the same position as the sixth sepal in the anomalous cases just referred to. In D. ferruginea, however, I have sometimes found a sixth sepal and a notched lip in the same flower. These anomalies may therefore be considered ana- logous phenomena among the supernumerary developments of the two organs. 3. JPollen. In comparing the action of the three pollens when immersed in water, I observed all the phenomena usually at- ' tendant on this experiment, to take place in those of purpurea and lutea: their grains quickly swelled and their granules were ex- ploded in the form of a dense cloud (Fig. F and Two kinds of granules were also observed, the smallest and most numerous of which were too minute for me to be able to ascertain their precise shape and dimensions by the highest powers of my in- struments; the others, much fewer in number, were considerably larger, and lay dispersed among the smaller like pel 1 ucid spots on a darker ground ; and these might even be distinguished through the coats of the grains before their expulsion had taken place. Some pollen of purpurea taken from a withering stigma exhibited very distinctly the presence of the exserted mem- branous tubes {boyaux) described by A. Brogniart, Amici, and others, in the Ann. des Sciences, (Fig. G). Some of the granules also were marked on the surface by three blotches (Fig. H). Grains of pollen taken from the hybrid readily swelled upon immersion in water, though most of them appeared to be void of granules. Some few however certainly contained the larger
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