92 LETTER XXXIV. 



Such distinctions would be more important, if many 

 more species, correspondino^ with one another in habit, 

 were found to possess them ; but as there is nothing 

 in the habit of Dionsea, materially at variance with 

 that of Sun-dew, and as only one species of the genus 

 has ever been seen, it is not considered absolutely 

 necessary to separate it from the Sun-dew Tribe ; espe- 

 cially as the position of the placentae at the base, 

 instead of the sides of the seed-vessel, is not esteemed 

 of any structural importance. Nevertheless, it is to 

 be remarked, that the flower-cjuie is not coiled up, in 

 a circinate manner, before the flowers unfold, that 

 there is no trace of a tendency in Dionsea, to open its 

 seed-vessel by valves, and that the loose integument of 

 the seed of Sun-dew has no parallel in Dionsea. 



Such are the principal circumstances deserving notice 

 in the fructification of the Venus' Fly-trap. Let us 

 now recur to the highly curious phenomenon from 

 which it derives its name. You have seen that the upper 

 surface of the blade of its leaf is extremely irritable, 

 so that, when it is touched never so gently, the two 

 sides collapse forcibly ; it has been said, that this irrita- 

 bility invariably resides in three bristles, similar to the 

 teeth of the margin, but much finer, and growing from 

 the surface of the leaf in a triangular order. Why it is, 

 or bv virtue of what power, the bristles possess the key 

 to the irritability of the Dionsea leaf, no one has ever 

 succeeded in discovering. The phenomenon seems to 

 belong to the extensive class of final causes which man 

 is not permitted to explain. We, moreover, find upon 

 the surface, a prodigious multitude of red glands, so 



