Clare Island Survey — Phanerogamia. 10 93 



soixante metres. Dans ces conditions-la. il est clair qu'aueun vestige de la 

 flore n'a pa subsister apres le cataelysine. La graine la plus persistante et le 

 rhizome le mieux protege ont do. perdre a jamais toute vitalite." 1 



Nevertheless, we must remember that a rich vegetation had been shedding 

 its seeds on the island uninterruptedly until the catastrophe destroyed it 2 ; that 

 floods, landslips, and other agencies must previously have buried countless 

 seeds, some to a considerable depth ; that seeds long buried in the soil are 

 often capable of germination as soon as opportunity arises; 3 and that the 

 rains (reckoned at 98 inches per annum, falling mainly in four months), which 

 rapidly denuded the beds of ash, cutting " deep valleys and gorges " within two 

 months (p. 4), must also have cut into the old surface, which had been left in 

 some places even devoid of volcanic covering (p. 4), though usually buried ; 

 many seeds might thus become exposed and scattered, which might germinate, 

 for heat does not readily penetrate downward, and seeds can survive a high 

 temperature. 4 



1 M. Treub : Notice sui' la nouvelle flore de Krakatau. Ann. du Jardin Bot. de Buitenzorg, 

 vii, 1888, pp. 214, 215. 



2 For instances of the vast number of seeds which the soil may contain the reader may consult 

 H. C. Long (Common Weeds of the Farm and Garden, p. 26. London, 1910), who took 1,050 

 seedling weeds off one square yard of well-weeded garden soil, and who quotes E. Korsmo's 

 observations (Kampen mod Ugraesset, 1906; of 1755, 10,332, and 33,574 seeds capable of germina- 

 tion, each contained in the soil of one square metre of agricultural land. From an Irish sample, 

 Adams has calculated 4,012,360 weed seeds as contained on an acre of ground (Irish Nat., xiv, 

 p. 80. 1905.) 



3 Long ago, A. P. de Candolle (Physiologie Vegetale, ii, 620. 1832) concluded that seeds buried 

 sufficiently deep in the soil to be protected from the action of air and moisture would have their 

 vitality much prolonged. Later C. de Candolle (Bibl. Universelle, Archives des Sciences Phys. et 

 Nat. (3), xxxiii, pp. 497-512. Geneve. 1895) and Giglioli (Nature, lii, pp. 544, 545. 1895) have 

 shown that seeds can display very remarkable resistance to severe conditions enduring many years. 

 In this connexion see also Duvel (U.S. Dept. Agriculture, Bureau of Plant Industry, Bull. 5S, 

 p. 80. 1904). Good instances of the vitality of seeds after many years' burial will be found in the 

 Irish Naturalist for 1904 and 1905, in communications by J. Adams and others. The cases quoted 

 by Clement Reid (I.e., p. 32) as instances of the rapid immigration of plants, in which Poppies and 

 Corn Marigolds appeared in quantity in ground laid bare in the making of new railways near Cromer 

 and Broekenhurst, would appear to be certainly due to this cause. A case similar to this last, and, 

 no doubt, correctly ascribed to long-buried seeds, is mentioned by Messrs. Sutton and Sons (Lawns, 

 p. 9. 1909) where a large rabbit-warren in Oxfordshire was dug and levelled, no extraneous 

 material being used, with the result that in the first year a dense growth of Brassica Sinapis appeared, 

 followed in the succeeding season by a crop of Ltjcltnis vespertina. On the other hand, Ewart's tests 

 in Australia of six hundred different sorts of old seeds, from herbarium and similar sources, showed, 

 on the whole, a very low vitality. (Quoted in G. H. Clark and J. Fletcher : Farm Weeds of 

 Canada, p. 13. 2nd ed. 1909.) Duvel's experiments (J. W. T. Di-vel : The Vitality of Buried 

 Seeds. U.S. Dept. of Agriculture, Bureau of Plaat Industry, Bull. 83. 1905) in burying seeds 

 suggest that this failure may have been due to temperature and moisture fluctuations. He buried 

 seeds of 109 species in porous flower-pots at various depths at Arlington, U.S.A., and found that 

 after a year, while the average germination was reduced to about one-half, that of the seeds buried 

 36-42 inches was half as high again as that of the seeds buried 6-8 inches. This result has an 

 obvious bearing on the point under discussion. Peter records the springing up of a great variety of 

 field plants after the removal of a forest which had occupied the ground for forty-six years. 

 (Quoted in Strasburger's Text-book of Botany, 3rd English ed., p. 322. 1908.) 



4 For the literature of this subject — the resistance of seeds to high and low temperatures — see 



