186 MR. T. Н. CORRY ON ASCLEPIAS CORNUTI. 
trivances ingeniously served a double purpose, 2. e. both for the process of extraction of 
the pollinia and for their insertion. 
This process was in the following year described independently by Prof. Friedric 
Hildebrand * in Asclepias, and in the spring of 1867 for this and other genera of the 
order as well by Delpino. Hildebrand supplemented his translation of Delpino's paper 
last mentioned, which he published in German in the autumn of the year in which the 
original appeared, with notes of some further observations of his own, and in particular 
with an account of the very remarkable movements which the pollinia undergo between 
the period of their extraction and that of their subsequent insertion into the fissure of 
an alar chamber. These movements he was the first to observe and draw attention to. 
The amount of labour independently bestowed by these last two observers upon the 
whole subject of the pollination of these flowers, and the value of the results at which 
they arrived, can scarcely be over-estimated. For myself, I may say that after several 
years of work on the subject, I have been not able to add very much, except in points | 
of detail, to what they have accomplished; and the testimony of others is the same. In 
Nov. 1870 J. P. Mansel-Weale t applied the results which had been previously arrived 
at to certain South-African genera and species of the natural order, viz. Gomphocarpus, 
В. Br., Xysmalobium, К. Br., Pachycarpus, Mey., Periglossum, Decaisne, and Cordylogyne, 
Mey.; and elicited the remarkable facts that in some Asclepiads no movements of the 
pollinia ever take place, that in others the movements are slight, while in Periglossum 
and Schizoglossum, Mey. (Aspidoglossum), it takes place in an entirely different and. 
even in a reverse direction from that presently to be described in the case of Asclepias 
Cornuti. Dr. Hermann Müller, in his admirable * Befruchtung der Blumen durch In- 
sekten,’ published in 1873 1, confirms the results of Hildebrand and Delpino, but adds 
little that is new, except that he details a very valuable list of the exact species of 
insects which are visitors to these plants, and the third part of his ‘Weitere Beobach- 
tungen über Befruchtung der Blumen durch Insekten,' p. 61, published in 1882, contains 
a supplementary list. 
B. Mode of Pollination. 
In fine weather (for in bad weather pollination is not effected), on the warm days of 
summer, numerous Hymenopterous insects,—viz. Wasps, especially Scolia hortorum and 
S. bicincía, and Bees, especially the Hive Bee and the Humble Bee, and also Flies— 
enticed by the sweet, heavy perfume of the flowers and the bright sunshine, alight on 
the umbel, to make use of the sweet nectar existing in the nectaries. The insect, alighting 
on a flower, takes up the position most convenient for sucking. It grasps the back of a 
nectary, and plunges its proboscis into its cavity, endeavouring at the same time to get 
+ « Ueber die Befruchtung von Asclepias Cornuti," Bot. Zeit. 1866, по. 48, pp. 876-380. “Пе Gesehlechter- Ver- 
theilung bei den Pflanzen,’ 1867, pp. 58-59 & 80. Fredric Delpino's “ Beobachtungen über die Bestüubungsvorrich- 
tungen bei den Phanerogamen, mit Zusützen und Illustrationen.” Bot. Zeit. 1867, nos. 34, 35, 36, рр. 266-270 & 
273, plate vii. figs. 1-5. “Е. Delpino's weitere Beobachtungen über die Dichogamie im Pflanzenreich, mit Zusiitzen 
und lllustrationen." Bot. Zeit. 23rd Sept. 1870, no. 38, pp. 604—606 (Ceropegia elegans), abridged translation in 
German of the * Ulteriori Osservazioni. Bot. Zeit. 1871, р. 746, note on Asclepias tenuifolia. 
+ “ Observations on the Mode of Fertilization of certain Species of Asclepiadew,” Journ. Linn. Soc. Bot. vol. xiii. 
pp. 48-58. от Pp. 334-338, figs. 122-123. 
