24 INSECT TRANSFORMATIONS. 



analogy, there is no difference more marked than in 

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

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

 while the seeds of plants are no less uniformly ditfu- 

 sable 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 ditfusion of the seeds of thistles^ 

 groundsel, dandelion, &c., by means of feathery 

 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 affinity 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 »oculament, 

 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 after 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 vioiacese, worthy of remark. 

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

 ing position, with the persisting calyx spread (jver it 

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

 which would retard the process of ripening; but no 



