SCIENCE. 



265 



be carried through absolute alcohol into turpentine, and 

 mounted in balsam at any time thereafter. If successful in 

 this staining you will have the pith cells in red, the spiral 

 tissue in blue, the wood cells in purple and the stellate 

 crystals in green or yellow. 



But the chief objects of interest to the microscopists in 

 the vegetation of Florida, are the insectivorous plants. Not 

 only are they more abundant, and, as I think, more per- 

 fectly developed in the central lake regions of Florida, but 

 some varieties are found there differing, it seems to me, 

 from any found elsewhere. I desire particularly to mention 

 one which I discovered, and which perhaps might be en- 

 titled to rank as a new species. 



In a lagoon-like basin at the side of a small lake near 

 Lake Harris, in water from two to three feet deep, 1 found 

 numerous specimens of the insectivorous plant known as 

 the Drosera or Sun-dew, growing thriftily and floating about 

 among the scattered water-weeds, without any attachment 

 whatever, indeed with very little root of any kind, the dead 

 leaves that hung down in the water seeming both to buoy 

 it up and to hold it upright. This plant differs from all the 

 described species of Drosera, so far as I have been able to 

 to ascertain, in having an upright, leaf-bearing stem from 

 four to five inches long, in floating free on the water, and in 

 having unusually long, vigorous and numerous leaves. As 

 I never found this floating Drosera in any other location, 

 and as there was an abundance of the ordinary Drosera 

 longifolia growing on the adjoining shore, I could not resist 

 the suspicion that at this 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 evo- 

 lution of a species in loco. 



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

 nearly all small ponds and permanently wet places through- 

 out 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 one slide. 

 Each leaf of the Drosera has, spread out on its upper sur- 

 face 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 incurved their 

 ends just meet at the centre 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 the 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 alight- 

 ing on these leaves is inevitably held fast. The tentacles 

 by which it is held very soon begin to bend towards the 

 centre 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 centre of 

 the leaf, in the course of an hour or two completely cover- 

 ing the captural prev. If the insect is caught entirely on 

 one side of the leaf, then only the tentacles of that side in- 

 flect. 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 

 prepare 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 development 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 atmosphere 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 beauti- 



ful object for the microscope, both in a natural state and 

 when prepared by double staining. 



I have found it qui'.e 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 will 

 show them in far greater luxuriance and beauty. The 

 stellate hairs of the Deutzia, the Crotons, and the Shepher- 

 dias are far more numerous and striking on the flower buds 

 than on the leaves. The mushroom glands which are found 

 on the leaves of the Saxifrage and Pinguicula, are multi- 

 plied many fold in number and attraciiveness on the calyx 

 and flower stem of these plants. So 1 regard that this was 

 once the case with the Drosera ; and that the mushroom 

 glands, which are now found on the flower, were then com- 

 mon to the leaves. A process of evolution has transformed 

 them on the leaves into those wonderful motile arms 

 adapted to the capture of insects, but has left them un- 

 changed on the flower, where that function would be of no 

 use to the plant. I occasionally find in my preparations a 

 solitary mushroom gland among the tentacles of the leaf — 

 a remnant of a race that has been supplanted. There is 

 found in Portugal a plant very similar to the Drosera, the 

 Drosophyllum, which has still only the mushroom glands 

 on its leaves, and catches insects in great quantity by load- 

 ing them down with the viscid secretion which these glands 

 abundantly pour forth. 



To exhibit the very delicate structure of the leaf and ten- 

 tacles of the Drosera, it is necessary to color them but 

 slightly. The danger will be in over-staining ; therefore, 

 after decolorizing and immersing for a few hours in the car- 

 mine solution, the specimens should be exposed to only a 

 very weak fresh solution of logwood for fifteen or twenty 

 minutes. If the anilin blue is resorted to at all, it must be 

 in a very weak solution. A mounting of a leaf and a stem 

 with flower buds in one cell in camphorated or carbolated 

 water, makes a very pretty and complete slide for the Dros- 

 era. 



The Utricularia is a floating, carnivorous plant which 

 grows in the shallow water of quiet ponds. On the surface 

 of the water from five to seven leaves are spread out like 

 the spokes of a wheel, and from the centre of these leaves 

 the plant sends upward its flower stalk and downward its 

 root-like branches, floating freely in the water. Among 

 the thickly branching fibres of these long submerged 

 stems, are perched innumerable little bladders or 

 utricles, not much larger than the head of a pin, 

 each provided with a mouth, at the bottom of a sort 

 of funnel of bristles, closed with a cunning little trap-lid 

 which opens inward, engulfing and imprisoning whatever 

 minute creatures or substances may happen to be resting on 

 it. In these sacks during the growing season, we will find 

 numerous microscopic water fleas, mites and beetles, with 

 grains of pine pollen and other floating particles. The 

 organic bodies will be found in all stages of digestion, 

 showing that the plant derives nourishment from such cap- 

 tured prey ; and apparently its only means of livelihood is 

 trapping. 



When taken from the water and dried under slight pres- 

 sure, the submerged portions of the Utricularia will be 

 found literally covered with diatoms ; and many very inter- 

 esting chrysalids of water-insects will be found attached to 

 them. These will all be washed off if the plant is bleached 

 in chlorinated soda. To preserve them it will be necessary 

 to remove the color in alcohol, and besides to handle very 

 carefully. The staining can only be single ; and I have 

 found a weak solution of eosin in water, to be the best 

 material for coloring, showing at the same time the structure 

 of the utricles and the captures contained in them. Speci- 

 mens of new growths, showing the just forming utricles 

 and the peculiar circinate mode of growth, should be in- 

 cluded on the slide. The mounting should be in campho- 

 rated water. 



The Pinguicula, another of the insectivorous plants, is 

 found abundantly on the more open plains, and not far from 

 wet places. It is a compact rosette of very light green 

 leaves, growing close to the ground, from the centre of 

 which rises a single flower-stalk, eight or ten inches high , 

 The leaves have their edges turned up, forming a shallow 

 trough, and on the upper surface are mushroom glands, 

 which exude a viscid secretion. Insects are caught and 



