HORTICULTUKAL SOCIETY. 207" 



The Venus fly-trap (Dioncea muscvpula) grows in a very limited 

 region in eastern United States, usually near swamps (Fig. 11), 

 Its leaves are also arranged in the form of a rosette around the 

 base of the flower stem, and lie more or less flat upon the surface 

 of the soil. Each leaf [Fig. 12 (1)] is composed of a spatula- 

 shaped flat stem, which in front is suddenly contracted to almost 

 nothing, and thence expands again into a round leaf. This latter 

 is divided by a rib into two equal halves, which have the posi- 

 tion to each other as the leaves of a half open book. The margin 

 of each leaf carries twelve to twenty long and pointed teeth, 

 which possess, however, neither glands nor other remarkable 

 organs. In the central space of each half are three very stiff 

 and pointed spines, which are always shorter than the marginal 

 teeth, and which do not point straight upward. These spines 

 are composed of elongated cells [Fig. 12 (3)], whose protoplasm 

 is in a constant and rather rapid motion. At the base of these 

 spines we find a very short cylindrical bolster composed of small 

 cells, which allow a bending of the spines. The individual 

 spines are rather stiff, and can not bend, but can be pressed upon 

 the surface of the leaf, the bolster forming a sort of joint. Be- 

 sides the bristles we find the whole surface covered with glands 

 [Fig. 12 (6)], each composed of twenty-eight small cells; they 

 have a carmine color and can secrete a slimy fluid. Pressure, the 

 shaking of the entire plant or of a leaf by winds or falling drops 

 of rain, even injuries upon the stems or upon the under side of 

 the leaf produce no visible changes, but as soon as the upper sur- 

 face is touched, then the halves of the leaf approach each other, 

 until the pointed teeth of their margins cross, and the insect 

 producing this sensation is held a prisoner [Fig. 12 (2)]. If the 

 insect only touched the glands this folding together is carried 

 out quite slowly, but if one of the six spines has been touched 

 ever so slightly, the folding takes place at once, in ten to thirty 

 seconds, and may be aptly compared with the sudden closing of 

 an open book. The marginal teeth interlace like the fingers of 

 our two hands; the formerly flat upper surfaces of the leaf are 

 made a little concave, so that they inclose a hollow space. 



The now following changes depend upon the duration of the- 

 excitement, and whether the enclosed substance contains food 

 or not. If the excitement is of a short duration, or if the cap- 

 tive is not suitable for food, the leaf soon assumes its normal po- 

 sition. Otherwise the halves press tightly together; all the 

 glands, dry before, secrete now a slimy, colorless, very acid fluid,. 



