52 



is enclosed in the tube of the corolla. Above this there is 

 a circle of filaments which completely close the tube, and pre- 

 vent anything entering to the surface of the stigma until it 

 has been impregnated with its own pollen. I examined a very 

 large number of flowers, and in all I could see no provision 

 except for self- fertilisation. It seemed to me scarcely possible 

 that any insect would force a passage down to the stigma, but, 

 as a matter of fact, insects scarcely ever visit these plants. I 

 once observed a butterfly (Danais ervpims) fluttering over the 

 flowers of a large bush of white and red Vhica, so I caught it 

 and examined the proboscis and head carefully with the 

 microscope, but could not see any trace of pollen upon either. 

 So we must regard the many varieties of this plant as dependent 

 upon some other cause tlian cross-breeding. 



The butterfly I have just mentioned is a recent introduction 

 to Australia from America. It is now very widely known 

 throughout the continent, and I have seen it from Adelaide to 

 Capo York. Quite recently immense flocks were met with by 

 a vessel in the Pacific, at a distance of some 300 miles from the 

 Australian coast. It is said to have been introduced by means 

 of a plant which is very common as a weed in all Southern 

 Queensland, and in the northern coast districts of New South 

 "Wales. This is AsclejJias curassavica, or cotton weed, as it is 

 called frequently. It has rather showy red and yellow flowers, 

 and was a favourite in gardens until it became troublesome. 

 So far it cannot be said to have spread mischievously, though 

 it is very abundant in all waste places throughout the district 

 specified. In the West Indies the dry and powdered root is 

 used as a substitute for ipecacuanha. In Australia it is very 

 much infested by a dark coloured aphis, which, no doubt, it 

 serves to spread throughout the country. 



Many garden plants have found the soil of Australia so 

 suited to their wants, and the climate so suitable also, that 

 they have gone out and " done for themselves," and have 

 become very overbearing in their prosperity. It is generally 

 found that these " settlers " are the species which readily get 

 naturalised in other countries. (Enothera hicmiis is an instance. 

 It is exceedingly abundant about the Bathurst plains, and is 

 rather annoying to farmers, as it takes up much good ground, 

 and no cattle will eat it. Verhascnm t]mi)sus, or mullein, is a 

 very constant companion, but not nearly so abundant. 



A very large quantity of useful land is almost destroyed in 

 matiy parts of New South Wales by the spread of the " Coch- 

 ineal cactus" (Opuntia vitlgaris'), and another, or, perhaps, two 

 more species. It is not a plant that one wouhl consider likely 

 to spread, and yet it has done so most disastrously along the 

 open lands of the Hunter Eiver. It renders the ground quite 



