A FLY-CATCHING PLANT. 



WILLIAM KERR HIGLEY. 

 Secretary of The Chicag-o Academy of Sciences. 



Queen of the Marsh, imperial Drosera treads 

 Rush-fringed banks, and moss-embroidered beds. 



— Erasmus Darwin, in The Botanic Garden, ijSg. 



SOME of the most interesting forms 

 of nature are not the most showy 

 and are not easily observed by 

 the untrained eye. Many of 

 their characteristics can only be known 

 by carefully conducted investigations, 

 both in the field and in the laboratory. 



The advance of science has shown 

 us that it is as natural forsome plants to 

 obtain much of their nourishment from 

 the animal world, by a true process of 

 feeding, as it is for animal forms to ob- 

 tain their sustenance, either directly or 

 indirectly, from the vegetable world. 



There are many species among the 

 lower orders of plants that are well 

 known animal parasites, but there are 

 also, among our more highly organized 

 flowering species, forms that impro- 

 vise a stomach and secrete an acid fluid 

 for the digestion of nitrogenous food 

 which is afterwards absorbed and used 

 in tissue building. These are in no 

 sense of the term parasites. 



Such a plant is our common round- 

 leaved sundew {Drosera rotundifolia, L.). 

 The generic name Drosera is from the 

 Greek, meaning dew. 



This rather insignificant, but pretty 

 little plant is distributed nearly 

 throughout the world, and is usually 

 found in bogs, or in wet sand near some 

 body of water. The flower stalk is sel- 

 dom more than six or eight inches in 

 height and bears very small white or 

 pinkish-white flowers. 



The interesting feature of this spe- 

 cies, however, lies in the rosette of 

 about five or six leaves growing from 

 the base of the stem. These leaves lie 

 upon the ground and are usually about 

 one-fourth to one-half of an inch in 

 length, and are generally nearly orbic- 

 ular in form. The upper side is cov- 

 ered with gland-bearing tentacles. The 

 glands are covered by a transparent 

 and viscid secretion which glitters in 

 the sunlight, giving rise to the com- 



mon name of the plant. There are 

 usually over two hundred tentacles on 

 each leaf and, when they are not irri- 

 tated, they remain spread out. The 

 viscid fluid of the glands serves as an 

 organ of detention when an insect lights 

 upon the leaf. The presence of an in- 

 sect, or, in fact, any foreign matter, will 

 cause the tentacles, to which it is ad- 

 hering, to bend inward toward the 

 center of the leaf and within a very 

 short time all the tentacles will be 

 closed over the captured insect, which 

 is soon killed by the copious secretion 

 filling its breathing apparatus. 



Though these sensitive tentacles are 

 not excited by either wind or rain they 

 are by the repeated touchings of a 

 needle, or any hard substance. It is 

 said that a fragment of hair weighing 

 but 1-78,740 of a grain will cause a per- 

 ceptible movement. 



By experiment it has been shown 

 that a bit of hard-boiled Q^g, or a frag- 

 ment of meat as well as an insect will 

 cause not only an inflection of the ten- 

 tacles but also of the edges of the 

 leaves, thus forming an improvised 

 stomach, the secretion of the glands then 

 increasing and becoming acid. At this 

 stage the secretion is not only capable 

 of digesting but is also highly anti- 

 septic. 



This power of digesting and absorb- 

 ing nitrogenous food is absolutely nec- 

 essary to the existence of the sundew, 

 for it usually grows in a poor soil and 

 its few and not greatly elongated roots 

 are of little service except to absorb 

 water, of which it needs a large amount 

 for the production of the copious secre- 

 tion. Specimens may be developed by 

 planting in moist cotton and furnishing 

 with plenty of water. 



The length of time that the tentacles 

 will remain inflected depends on the 

 vigor of the leaf and the solubility of 

 the material causing the excitement. 



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