192 



THE AMERICAN MONTHLY 



[October, 



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 prob- 

 ability 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 expan- 

 ded leaves forms a circlet as beauti- 

 ful as any flower, and often so very 

 small that I have frequently moun- 

 ted whole plants with flower-stalk 

 and buds on one slide. Each leaf 

 of the Drosera has, spread out on its 

 upper surface and edges, from two 

 to three hundred arms, called tenta- 

 cles because endowed with the power 

 of motion, and of such varying 

 lengths that when naturally incur- 

 ved their ends just meet at the cen- 

 ter of the leaf. Each tentacle has 

 at its extremity a pad, like an exten- 

 ded palm, with a ridge raised length- 

 wise upon it, and in this palm is a 

 bundle of spiral vessels connected 

 with the same tissues in the leaf. 

 Now aU 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, car- 

 rying 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 cov- 

 ering 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 the 

 plant all this nutritious little feast. 

 In the course of three or four days 

 the tentacles again expand and pre- 

 pare themselves for another capture. 



There are several reasons which 

 lead me to believe that these unique 

 and most wonderful organs of the 

 Drosera are a direct and special de- 

 velopment from the common, simple 

 mushroom glands, which are found 

 on many plants, and which have 

 for their primary function to absorb 

 moisture and ammonia from the at- 

 mosphere and from rains. I found 

 on the calyx and flower stem of the 

 Drosera an abundance of these 

 mushroom glands. Indeed the 

 flower stem with its buds furnishes 

 by reason of them, an exceedingly 

 beautiful object for the microscope, 

 both in a natural state and when 

 prepared by double staining. 



I have found it quite a general 

 rule as regards plants, that whatever 

 organs, such as stellate hairs or 

 glands, the leaves may possess, the 

 calyx and stem of the flower wiU 

 show them in far greater luxuriance 

 and beauty. The stellate hairs of 

 the Deutzia, the Crotons, and the 

 Shepherdias, are far more numerous 

 and striking on the flower buds 

 than on the leaves. The mush- 

 room glands which are found on the 

 leaves of the Saxifrage and Pingui- 

 cula, are multiplied many fold in 

 number and attractiveness on the 

 calyx and flower stem of these plants. 

 So I regard that this was once the 

 case with the Drosera ; and that the 

 mushroom glands, which are now 

 found on the flower, were then 

 common to the leaves. A process 



