24 INSECT TRANSFORJNIATIOXS. 



analogy, there is no difference more marked than in 

 this very point — that the eggs of insects are, in most 

 cases, fixed by a gkie at the moment of exclusion, 

 while the seeds of plants are no less uniformly 

 diffusable and free. The fertile seeds of plants, 

 it is true, are heavy enough to sink in water, and 

 consequently as much unfitted for floating in the 

 air as the eggs of insects; but the contrivances to 

 counteract this exemplify some of the most beautiful 

 provisions of nature. The diffusion of the seeds of 

 thistles, groundsel, dandelion, &c, by means of feath- 

 ery down, attracts the notice of the most incurious. 

 Another contrivance of nature for effecting the same 

 purpose is not only curious in itself, but bears upon 

 our present subject as illustrating an aflinity which it 

 may be supposed to have with the ovipositing of certain 

 insects. 



The seeds of the various species of violets are 

 contained in a capsule of a single cell, or loculament, 

 consisting, however, of three valves. To the inner 

 part of each of these valves a seed is attached, and 

 it remains so for some time alter the valves, in the 

 process of ripening, have separated and stood open. 

 The influence of the sun's heat causes the sides of 

 each valve to shrink and collapse; and in this state 

 the edges press firmly upon the seed; which, it may 

 be remarked, is not only extremely smooth, polished, 

 and shining, but regularly egg-shaped. Thus, when 

 the collapsing edge of the valve slides gradually 

 and forcibly down over the sloping part of the seed, 

 it is thrown with a jerk to a considerable distance 

 There is another part of the contrivance of nature for 

 the same purpose, in the violacefe, worthy of remark. 

 Before the seed is ripe, the capsule hangs in a droop- 

 ing position, with the persisting cal}x spread over it 

 like an umbrella, to guard it iiom the rain and dews, 

 which would retard the process of ripening: but no 



