88 



THE GAIWENElVt> MONTHLY 



[March ^ 



Mo^^THLY ill trying to demoustrate the truth or 

 falsity of Mr. Francis Darwin's conclusions, 

 are briefly as follows : Mr. Darwin cultiva- 

 ted a number of Sundews, one form of in- 

 sect-eating plants, feeeding one-half with fibres 

 of beef and not so feeding the rest, and when 

 the plants were grown he counted and weighed 

 the leaves and seeds, and also weighed the plants 

 bodily, and in every case he found the advantage 

 was on the side of the beef-fed plants. The 

 leaves were more numerous, the flower stems 

 taller and more vigorous, the flowers more 

 numerous, the seeds more numerous — in every 

 respect demonstrating that these plants did derive 

 nourishment from this animal food. Now these 

 are the facts as given on one side, which of 

 course may be questioned by other careful investi- 

 gators. Now let us examine closely the charac- 

 ter of the plants experimented upon, and in 

 them we may find more difierence than in the 

 character of the food or the care of the investi- 

 gators, who are doubtless both correct in their 

 facts. 



It will be noticed Mr. Darwin experimented 

 on Sundews, the common name of a species 

 of Drosera, from drocei-os, dewy. These are an 

 order of delicate herbaceous marsh plants of the 

 south of Europe and ranging up to the tropics. 

 There are about forty species of Drosera found 

 in boggy places all over the world, except in the 

 extremes of heat and cold. The Dionaja, or 

 Fly-trap, is also placed in this order by many 

 botanists. The Sundews, as commonly called, 

 are remarkable for their singular red colored 

 glandular hairs, which discharge a viscid acrid 

 fluid in which insects are caught. The British 

 species of the order with which Mr. Darwin doubt- 

 less experimented are all noted for this pecu- 

 liarity, especiilly the variety often found near 

 Loudon and elsewhere, Drosera rotundifolia, or 

 round-leaved Sundew; this has the leaves close 

 to the ground, nearly circular and spreading, 

 with a roundish limb tapei'ing into a hairy 

 petiole. Its secretions are very acrid and caus- 

 tic, and in Italy the liquor called rossali is dis- 

 tilled from its juices. Itcurdles milk, and is said 

 cures corns and warts. Several of the foreign 

 species have also the reputation of being poison- 

 ous, notabl}' D. communis to sheep and cattle, 

 while D. lunata has viscid leaves and glandular 

 fringes which close upon insects happening to 

 touch them, in this respect resembling Dionsea 

 muscipula, but this is one of the exceptions in 

 this class. While all are ornamented with red 



glandular hairs, discharging from their ends a 

 drop of viscid acrid juice, the Drosera rotundi- 

 folia when seen luxuriating on living sphagnum 

 moss in a cool house resembles an emerald set 

 with a thousand little rubies, the beauty aiv 

 parently enticing the insects which often be- 

 come entangled on alighting and die. 



Now I think the object of this is not diffi- 

 cult to understand. All decaying animal matter 

 gives off" ammonia, and a portion of this is no 

 doubt decomposed by the plant to furnish the 

 nitrogen which the plant requires. But as only 

 a certain amount ofthis can be utilized by the 

 plant, and if this amount can be obtained from 

 the soil or surrounding air, any excess provided 

 to the plant in the way of insects or flesh, could 

 give no appreciable effects. So that the question 

 of conditions of soil, may become an important 

 factor as well as the difierence in the nature of 

 the plants. The power of catching insects is 

 undisputed, but the object of this power and the 

 utility of it, is the question which the consider- 

 ation of the next jjlant Dionsea muscipula may 

 assist us somewhat in reaching. This is the 

 plant Mr. Henderson tried the effects of feeding 

 with flies and other insects for several montlis, 

 and as the feeding did not "fatten" it completely 

 failed to sustain or corroborate Mr. Darwin's 

 test. This plant is said to be originally from 

 South America, although now found plentifully 

 in North Carolina. There is but one species of 

 this order, muscipula, a fly-trap. Its leaves 

 which are spread out on the soil near the roots 

 are composed of two parts, the one elongated 

 and terminated by two rounded plates or leaves, 

 furnished with hairs on their outer edge. When 

 touched these outer leaves close upon their 

 victim and remain closed so long as the insect 

 continues to struggle, but as soon as it is quiet 

 the leaf opens and permits it to escape. These 

 plates are also furnished with certain small 

 glands in the upper surface whence exudes a 

 viscuous liquid. But this does not appear to 

 assist in retaining the animal. The retaining 

 power in this instance being in the irritability of 

 the plant acting on the nervure at the base, which 

 is fashioned like a hinge, as when the efforts of 

 the insect to escape ceases, irritabilit}' ends and 

 the plant returns the two trap like nets to their 

 former position. Should the fly or insect how- 

 ever continue its efforts to escape, the plant will 

 remain shut until exhaustion or death prevents 

 ftirther movements against the sides of these 

 singularlv irritable leaves, which irreatly resem- 



