DISPERSION OF SEEDS. 27 



sects and the plants which discharge their seeds, 

 will disappear, when we consider that the scattering 

 of the seeds is, in the plants, a regular and con- 

 stant process of nature; whereas the insects only jet 

 out their eggs from fear when caught. The power 

 of throwing their eggs to a distance, indeed, could 

 be of no possible use to insects, because they pos- 

 sess the more efficient power of locomotion. 



The facts which we have thus stated with regard 

 to the seeds of plants being diffused by the means 

 of winged down, or by the more remarkable capacity 

 of being projected, differ, as we have shown, in some 

 important circumstances from the nearly similar ar- 

 rangement of nature in the economy of insects. 

 They constitute affinities, but not analogies. On the 

 other hand, the more universal law of the conti- 

 nuance of insect life by every new generation being 

 hatched from eggs, may be illustrated by an analogy, 

 which is observed even in the most minute instances, 

 in the generation of plants from seeds. 



The diffusion of the seeds of an extensive order 

 of plants (CryptogamicB) LINN., Jlcotyledones , Juss., 

 CellulareSj DE CANDOLLE) being so universal, and 

 the seeds (sporules) themselves being so minute as 

 to elude common observation, the phenomena thence 

 arising have, like the sudden appearance of newly 

 hatched insects, given some colour to the doctrine of 

 spontaneous generation. We may see this exem- 

 plified every day on brick walls recently built, even if 

 they be covered with a smooth coat of cement. The 

 first indication of vegetable life on such a wall, par- 

 ticularly in parts exposed to the trickling down of 

 rain water, is that of a green silky-looking substance, 

 having somewhat the appearance of a coat of green 

 paint. Mr Drummond, of the Cork Botanic Garden, 

 by accurately watching the progress of this green 

 matter, which had been unsuccessfully investigated 



