DISPERSION OF SEEDS. 29 



mosses are wafted to the walls tlirouoh tlie air, or 

 adopt the hypothesis that they have existed for cen- 

 turies in the interior of the rocks of the quarry. That 

 it is not impossible the seeds may have existed in the 

 rocks several curious facts would lead us to believe. 

 Some seeds, for example, retain the power of germi- 

 nating^ for an indefinite length of time; since the 

 wheat usually wrapt up with Egyptian mummies will 

 often germinate and grow, as well as if it had been 

 gathered the preceding harvest. It also bears upon 

 this subject, that when a piece of ground, which has 

 never been tilled, is turned up by the spade or tlie 

 plough, it immediately becomes covered with a crop 

 of annuals, not one of which may grow within many 

 miles of the spot; and a number of them, such as 

 hedge mustard {Hisymhrium officinale) and chick- 

 weed {Aldne media), whose seeds are not winged. 

 It is no less worthy of remark that all these annuals 

 will again disappear as soon as the grass is suffered 

 to spread over the spot which has been dug up. It 

 is mentioned by Mr. James Jennings, in Time's 

 Telescope for 1823, that the coltsfoot (Tussilago 

 farfard) is usually the first plant which appears in 

 England in such cases — a circumstance by no means 

 remarkable, as the seeds of this plant are winged with 

 down, and extremely light. 



A still more minute family of cryptogamic plants, 

 and consequently more difficult to trace, is well known 

 by the popular name of mould or mouldiness (Mu~ 

 cedines, Linn.) This, Adolpe Brongniart justly 

 remarks, is, in one of its groups, nearly allied to the 

 putf-balls (JLycoperda), whose mode of diffusing their 

 seeds we have just described. When mould is exa- 

 mined by the microscope it is seen to resemble these; 

 and sometimes various fungi are, when mature, filled 

 ■with a blackish dust, suppot^ed to be the seed. 

 MicheU, of Florence, an eminent botanist, resolved 



■^3 



