MICROSCOPICAL COLLECTIONS IN FLORIDA. 137 



growing on the adjoining shore, I could not resist the suspicion 

 that at tin's very spot in some past time a plant of the longifolia, 

 had by accident become uprooted, and floated out on the water ; 

 that finding it could capture insects even better on the water than 

 crowded among shore plants, it adapted itself permanently to its 

 new location and modes of growth. It appeared to me quite 

 within the bounds of probability that here was an instance of 

 the evolution of a species in loco. 



The Drosera or "sun-dew" is found on the margins of nearly 

 all small ponds and permanently wet places throughout the 

 south. It is a small red plant, growing close to the ground, and 

 glistening in the sunlight. Its little whorl of expanded leaves 

 forms a circlet as beautiful as any flower, and often so very small 

 that I have frequently mounted whole plants with flower-stalk 

 and buds on an ordinary slide. Each leaf of the Drosera has, 

 spread out on its upper surface and edges, from two to three 

 hundred arms, called tentacles because endowed with the power 

 of motion, and of such varying lengths that when naturally in- 

 curved, their ends just meet at the center of the leaf. Each 

 tentacle has at its extremity a pad, like an extended palm, with a 

 ridge raised lengthwise upon it ; and in this palm is a bundle of 

 spiral vessels connected with the same tissues in the leaf. Now 

 all these tentacles secrete and exude from the glands at their 

 ends a little drop of a very adhesive fluid ; and the glistening of 

 these drops in the sunlight on their usually bright red back- 

 ground, gives to the plant its beauty and its name of the " sun- 

 dew." An insect attracted to and alighting on these leaves is 

 inevitably held fast. The tentacles by which it is held very 

 soon begin to bend towards the center of the leaf, carrying the 

 fly with them. Then in some mysterious way, intelligence is 

 communicated to the other tentacles, and they too begin to turn 

 towards the center of the leaf, in the course of an hour or two 

 completely covering the captured prey. If the insect is caught 

 entirely on one side of the leaf, then only the tentacles of that 

 side inflect. The glands after envelopment, exude a gastric fluid 

 which dissolves the nitrogenous matter in the body, after which, 

 by another change of function, they absorb and carry down into 



