On Spontaneous Generation. 375 



larity of the types of the two kingdoms of nature is quite 

 striking, which has often been observed with regard to New 

 Holland ; and if there still be philosophers who are inclined 

 to think that the Casuarina was planted, and that the Casu- 

 ar walked about in the garden of Eden, and was afterwards 

 received into Noah's ark, I wish they would tell us how a 

 bird that can neither fly, nor likes to go into an element where 

 it would soon be drowned, has got to New Holland after the 

 deluge, or why this bird is not found at a reasonable distance 

 from mount Ararat, or on the old continent at all. The num- 

 ber of the species, moreover, bears a direct proportion to the 

 extent, climate, and variety of soil, of any particular country; 

 wherefore Du Petit Thouars found only 113 phanerogamous 

 and cryptogamous plants on the island of Tristan d'Acunha, 

 and De Buch observed that the flora of the Canary islands is 

 comparatively poor, which is sufficiently explained by the lit- 

 tle variety of formation in these volcanic islands. That the 

 nature of the soil is the great agent in determining the spon- 

 taneous generation of plants, and that the climate acts only a 

 subordinate part, within certain limits, may be proved by the 

 instance of the birch, whose natural breeding-ground appears 

 to be alluvial quartz-sand, strongly impregnated with humic 

 acid. Now, though this tree can bear a greater degree of cold 

 than any, we find it in the Alps of Tyrol very far below the 

 line of perpetual snow, immediately below the Scotch fir, 

 above which appear the pine, (Pinus Abies, L.), and larch ; 

 whereas in the north of Scandinavia, where its congenial soil 

 reaches up to the snow-line, it is above the Scotch fir, after 

 which follows the pine lower down.* The nature and order 

 of the respective soils no doubt fully accounts for this curious 

 inversion of the order of vegetation. 



Among the many observations made within the last twenty 

 or thirty years, which may be brought forward as proofs of 

 the generatio cequivoca still going on, on a large scale, with 

 respect to plants, and which the opposers of that doctrine 

 have, with great self-complacency, laid hold of to prove their 

 assertion that the surface of the earth swarms with seeds, de- 

 posited there many thousand years ago, I shall select a few, 

 and support them by observations of my own. 



Where a new alluvium is formed, or an ancient one laid 

 dry, the ground soon covers itself with plants exactly adapt- 

 ed to its nature. A fish-pond having been drained near Fre- 

 dericksberg,Mr. Holboll found on that spot Car ex cyperoides,\ 



*Blockein die ostlichen Alpen, &c. von Canstein, Berlin, 1837. 

 f Viborg, im Magazin der natnrforsehenden Freunde zu Berlin, 1808. 

 Vol. II.—No. 19. n. s l l 



