02 



THE AQUARIUM, JULY, 1893. 



country he fled, his celebrated gold 

 water (Aquae auri), from the plant, 

 which should heal all diseases, so that ■ 

 it was made into a pleasant tasting 

 mixture, under the nxme of Rosoglio 

 (from Ros soJis, sun-dew), and it is still 

 to this day prepared and used in Italy. 

 The German botanist Roth in the year 

 1779 was the first to describe the nature 

 and use of these so-called dew drops. 

 He noticed on several small hairs bent 

 to a central point, and also that the 

 margin of the leaf was slightly curled 

 towards the centre. When he exam- 

 ined several of these closed leaves he 

 generally found inclosed a more or less 

 decomposed insect. The closed leaf he 

 compares to a many fingered fist. On 

 this discovery he planted several speci- 

 mens in pots at his home, so as to be 

 able to more accurately observe their 

 nature. When a live ant or small bug 

 was placed on the surface of the leaf, it 

 was observed that the exuded fluid 

 adhered to the feet of the insect and 

 forming small threads, in this way pre- 

 venting its escape. After a short 

 period the hairs on the leaf were 

 noticed to bend upon themselves, and a 

 little later the marginal hair also. It 

 took several hours before the leaf had 

 completely closed, when it resembled a 

 new leaf making its appearance. The 

 same careful observer also noticed that 

 they were more sensitive in warm air and 

 sunshine than during cold and rainy 

 weather. Further observations showed 

 that they were not so sensitive to inor- 

 ganic substances, as to live insects, also 

 that the long leaved plant to possess it- 

 self of its prey rolled up on itself from 

 the point, while in the RofundifoUa, it 

 merely formed a trough, the work of de- 

 struction being carried on by the hair. 

 These repeated observations of differ- 

 ent botanists were not further studied 



for eighty years, until recently, when 

 the plants again attracted the attention 

 of naturalists. Besides the English 

 naturalists, Darwin and Bennett, and 

 the Frenchman Ziegler, an American 

 lady, Mrs. Mary Treat, of Carolina, has 

 distinguished herself as an observer of 

 these plants. She experimented with 

 ordinary ones found in the swamps, and 

 also with the more rarer one, the Drosera 

 filifera, and saw not only small insects, 

 such as ants, spiders and flies caught, 

 but sometimes larger ones, such as the 

 ordinary miller, which flies around our 

 lamps during summer evenings. If she 

 placed insects or small pieces of raw 

 mtat on the leaves during the warm 

 hours of the day, it was observed that 

 the leaf soon commenced to fold up, 

 which was generally complete in two 

 hours. While a piece of raw meat 

 irritated it as readil}^ as an insect, such 

 substances as grains of salt, pieces of 

 lime, grains of corn, etc., had no effect in 

 twenty-four hours. Wet lime naturally 

 irritated on account of its caustic prop- 

 erties. There is no doubt that the leaf 

 has the power of distinguishing between 

 mineral and animal substances. Mrs. 

 Treat even believes to have observed 

 that they are acted on by these from a 

 distance, because in July, 1873, she 

 fastened a living fly at a distance of one- 

 half an inch above the leaf, and after 

 forty minutes noticed that it was 

 strongly bent upwards, and in ten 

 minutes more had seized it Avithin its 

 arms of prey. 



[To he Continued.) 



A Reference Table in shape of a 

 bookmark, containing the Fahrenheit, 

 Celsius and Reaumur thermometer 

 scales, inch and centimetre measure, 

 foreign money, etc., sent gratis on re- 

 ceipt of two cents postage. 



Address The Aquarium. 



