322 REPORT UPON COTTOX INSECTS. 



The reproductive organs are so placed that on the expansion of the 

 corolla pollen has usually been deposited on the stigmas, self-fertiliza- 

 tion being thus secured. By his many observations and experiments, 

 Darwin has shown that where self-fertilization is thus provided for, oc- 

 casional crossing is often of sufficient importance to warrant the pro- 

 duction of large and conspicuous corollas, and of nectar accompanied by 

 fragrance to secure such crossing by inducing suitable animals to go 

 from flower to flower. Such appears to have been the case here, for 

 within the corolla, where the petals separate from one another and from 

 the staminal column, is found a set of small hairs which are slightly 

 viscid as shown by the adhesion of pollen grains to them. What causes 

 this viscidity f Early in July I noticed a single hive bee within a cot- 

 ton flower, where, as I then supposed, it had gone to collect pollen, 

 but I failed to see that it did. About the same time I saw many hum- 

 ble-bees entering the flowers for pollen as I thought, and they, too, went 

 unnoticed, though they transferred much pollen from flower to flower in 

 these visits. Shortly afterward I noticed certain sand-wasps belonging 

 to the genus Elis within the flowers, and as I did not know that they 

 fed on pollen I was led to watch their actions. Instead of collecting 

 this substance they were exploring with their tongues the clefts between 

 the petals; this led me to examine a flower more closely, the result 

 being the finding of the hairs just mentioned. As no nectar was found 

 elsewhere in the flowers, and as these insects were constant in their 

 visits, I infer that viscidity of the hairs is caused by an exudation of 

 true nectar. * Darwin describes a similar secretion from hairs on the 

 labellum of Cypripedium. t 



lumbers of specimens of the beetle Chauliognatlius marginatm were 

 found within the flowers, where, however, they ate only pollen, so far 

 as I could see. Individuals of the yellow butterfly Callidryas cubule 

 \rere often seen resting on the free border of the petals and sipping the 

 nectar with their long and flexible proboscides. The following-named 

 insects were all seen in greater or less numbers in the flowers after 

 nectar: Ells 4-7iotato, Elis plumipes, Melissodes nigra, Mcgachile sj>., aud 

 Bombus sp. 



In thus collecting pollen and nectar, these insects, with the exception 

 of the butterfly, coming in contact with both anthers and stigmas, became 

 well dusted with pollen, which necessarily was transferred in quantity 

 from flower to flower. The species most frequently met with in these 

 flowers were Elis plumipcs $ and Mclissodes nigra. 



As an example of extralloral nectar produced on the calyx, I shall 

 cite that of the leguminous plant, Coronilla varia, described by Farrer.f 



" 111 the Popular Science Review for July, 1869, p. 270, Ogle states that, as proviously 

 noticed by Vaucher, no nectaries are found iii Synacnic Malvaceae. This appears to 

 be an exception to that rule, for, so far as I could see, the stigmas were perfectly re- 

 ceptive when the corolla expanded. 



t Fertilization of Orchids, second edition, p. 229. 



I Nature, x, 1874, p. 1G9. 



