Sudden Appearance of Plants. 3 
who have the opportunity and the necessary leisure, should take 
the subject up and remove it from the regions of empiricism to 
those of certainty. ‘The necessary experiments could easily be 
conducted on a well-exposed piece of land of moderate size, by 
turning over the soil in contiguous areas at different seasons, and 
by the judicious use of gauze and glass work. 
Confining our attention to the evidence before us, there is, at 
least, one test that must appear as crucial in settling the relative 
merits of the two theories. If the seeds are wind-borne, no soil 
which is turned over in spring will produce its crop of new plants 
until the following year, that is, until the plants of the same 
species in the neighbourhood have seeded. While in Lincoln- 
shire, during the present year, my attention was called to a case 
in which a ditch had been dug in the early spring, and in the 
same year a crop of thistles sprang up all along the newly-turned 
soil. Now, it is quite evident that any pre-existing thistles in the 
neighbourhood could not have been in seed at that time ; indeed, 
they would scarcely have commenced to send up their stems. As 
a matter of fact, however, there were no thistles for a considerable 
distance round. In this case, then, the thistle seeds must have 
been buried in the soil. 
Mr. A. Bennett, of Croydon, in a communication to Mr. 
Wallace, states that the first year after the railway from Yarmouth 
to Caistor, in Norfolk, was made, the banks produced abundance 
of C@nothera odorata and Delphinium ajacis (the latter only 
known thirty miles off). The new introductions, however, 
gradually disappeared, giving way to the native plants. A similar 
phenomenon was noted by the same observer between Chesterton 
and Newmarket, in Cambridgeshire, where Sée//aria media, and 
other annuals appeared in large patches, and in about three years 
disappeared. Neither De/piinium nor Stellaria has seeds which 
are likely to be carried by the wind. Mr. T. Kirk states that in 
Auckland the fiddle dock (Rumex pulcher) occurs in great abun- 
dance on the formation of new streets, etc., but soon becomes 
comparatively rare. He thinks it probable that it was one of the 
earliest plants naturalised there, but that it partially died out, its 
buried seeds retaining their vitality. 
In a letter to the Pharmaceutical Journal of April 25, 1885, 
I called attention to the sudden appearance of an abundance of 
fyoscyamus niger and Sinapis alba on the earth turned over in 
making a new road on the island of Inchkeith, in the Firth of 
Forth, and to the fact that they are now gradually dying out, the 
former having almost entirely disappeared. On making further 
inquiry into this case, I find it gives greater probability to the 
buried seed theory than I at first supposed. On my first visit to 
the island the plants were in flower and as the henbane only 
