tH INSECT TRANSFORMATIONS. 



by Priestley, Iiii^euhouz, and Ellis, and had been 

 mistaken by Linnicus for a crop of />?/s\s/, ascertained 

 beyond quesiion that it always consisted of the 

 minute buds of common mosses, such as the wall 

 screw moss {Tortula muralis) and the common hair- 

 hood moss (^Polytrichmn commune)*. At Glasgow, 

 xve have repeatedly remarked, that o!i the walls of 

 houses, built with freestone raised from a quarry 

 more than a hundred feet under the surface of the 

 soil, the whole exterior would, in the course of one 

 month, appear as green as if painted, with these in- 

 numerable germinating' mosses +. 



The germination of mosses on walls appears to 

 arise from the seeds {sporides) being carried into the 

 air. This process is iacilitated by their extreme mi- 

 nuteness and their comparative lightness, for they 

 do not sink in water like the seeds of phenogamous 

 plants and the eggs of insects, as appears from their 

 germinating on the surface of stagnant water as 

 frequently as on walls. In low situations, the mode 

 in which the seeds of cryptogamic plants are ditfused 

 is well exemjjlitied in tlie puif-ball {Lycoperdon)^ 

 which, when ripe, explodes its sporules in the form 

 of a smoke-like cloud. Mosses again, which grow 

 on trees and walls, if they do not thus explode their 

 sporules, must drop them into the air ; and, as they 

 chiefly ripen early in spring, the winds which then 

 prevail will scatter them to considerable distances. 

 But we omly state this as a highly probable inference 

 from Drunimond's discovery: to detect these all but 

 invisible seeds floating in the atmosphere, and trace 

 them in their passage from the parent plant to the 

 wall or tree where they begin to germinate, we think- 

 is hardly possible. 



If the doctrine be sound, that every plant arises 



from seed, we must either believe that iniwimerable 



* Liiiii. Trans. f J. K 



