368 



NATURE 



{Sept. 3, 1874 



into fine threads. In some minutes the short hairs on the disc 

 of the leaf began to bend, then the long hairs, and laid them- 

 selves upon tire insect. Aftei' a while the leaf began to bend, 

 and in some hours the end of the leaf was so bent inwards as to 

 touch the base. The ant died in fifteen minutes, which was 

 before all the hairs had bent themselves." 



These facts, established nearly a century ago by the testimony 

 of independent observers, have up to the present tiroe been 

 almost ignored; and Trecul, writing in 1855, boldly asserted 

 ihat the (acts were not true. 



More recently, however, they have been repeatedly verified : 

 in Germany by Nilschke, in i860; in America by a lady, Mrs. 

 Treat, of New Jersey, in 1S71 ; in this country by Mr. Darwin, 

 and also by Mr. A. W. liennett. 



To Mr. Darwin, who for some years past has had the subject 

 under investigation, we are indebted, not merely for the complete 

 confirmation of the facts attested by the earliest observer.':, but 

 also for some additions to those facts which are extremely im- 

 portant. The whole investigation still awaits publication at his 

 hands, but some of the points which were establishrd have been 

 announced by Professor Asa Gray in America, to whom Mr. 

 Darwin had communicated them. 



Mr. Darwin found thai the hairs on the leaf of Drosera re- 

 sponded to a piece of muscle or other animal substance, while to 

 any particle of inorganic matter they were nearly indifferent. 

 To minute fragments of carbonate of ammonia they were more 

 responsive. 



I will now give the results of Mrs. Treat's experiments, in her 

 own words : — ■ 



" Fifteen minutes past ten I placed bits of raw beef on some 

 of the most vigorous leaves of Drosera longifolia. Ten minutes 

 past twelve two of the leaves had folded around the beef, hiding 

 it fromsiglit. Half-past eleven on the same day, I placed living 

 flies on the leaves of D. loni;iJ'oHa. At twelve o'clock and forty- 

 eight minutes, one of the leaves had folded entirely round its 

 victim, and the other leaves liad ]5artially folded, and the flies had 

 ceased to struggle. By half-pist two, four leaves had each folded 

 around a fly. The leaf folds from the apex to the petiole, after 

 the manner of its vernation. I tried mineral substances, bits of 

 dried chalk, magnesia, and pebbles. In twenty-four hours 

 neither the leaves nor the bristles had made any move in clasping 

 these articles. I wetted a piece of chalk in water, and in less than 

 an hour the bristles were curving about it, but soon unfolded 

 again, leaving the chalk free on the blade of the leaf." 



Time will not allow me to enter into further details %\ith 

 respect to DionLiia and Drosera. The repeated testimony of 

 various observers spreads over a century, and though at no time 

 warmly received, must, I think, satisfy you that in this small 

 family of the Droseracen.' we have plants which in the first place 

 capture animals for purposes of food, and in the second, digest 

 and dissolve tliem by means of a fluid which is poured out lor 

 the purpose ; and thirdly, absorb the solution of animal matter 

 which is so produced. 



Before the investigations of Mr. Darwin had led other persons 

 to work at the subject, the meaning of these phenomena was 

 very little appreciated. Only a few years a^o, Duchartre, a 

 French physiological botanist, after mentioning the views of 

 Ellis and Curtis with respect to DionKa, expressed his opinion 

 that the idea that its leaves absorbed dissolved animal substances 

 was too evidently in disagreement with our knowledge of the 

 function of leaves and the whole course of vegetable nutrition 

 to deserve being seriously discussed. 



Perhaps if the Droseracen; were an isolated case of a group of 

 plants exhibiting propensities ol this kind, there might be some 

 reason for such a criticism. But I think I shall be able to sho-v 

 you that this is by no means the case. We have now reason to 

 believe that there are many instances of these carnivorous habils 

 in different parts of the vegetable kingdom, and among plants 

 which have nothing else in common but this. 



As another illustration I sl-.all take the very curious group of 

 Pitcher-plants which is peculiar to the New World. And here 

 also I think we shall find it most convenient to follow the his- 

 torical order in the facts. 



SarnueiiiiX. —The genus Sarracenia consists of eight species, 

 all similar in habit, and all natives of the Eastern States of 

 North America, where they are found more especially in bogs, 

 and even in places covered with shallow water. Their leaves, 

 which give them a character entirely their own, are pitcher- 

 shaped or trumpet-like, and are collected in tufts springing im- 

 mediately from the ground ; and they send up at the flowering 



season one or more slender stems bearing each a solitary flower. 

 This has a .singular aspect, due to a great extent to the imibrella 

 like expansion in which the style terminates ; the shape of this, 

 or perhaps of the whole flower, caused the first English settlers 

 to give to the plant the name of Side-saddle Flower. 



Sarracenia purpurea is the best known species. About ten 

 years ago it enjoyed an evanescent notoriety from the fact that 

 ils rootstock was proposed as a remedy for small-pox. It is 

 found from Newfomidland southward to Florid 1, and is fairly 

 hardy under open-air cultivation in the British Lies. At the 

 commencement of the seventeenth century, Clusius published a 

 figure of it, from a sketch which found its way to Lisbon and 

 thence to Paris. Thirty years later Johnson copied this in his 

 edition of Gerard's Herbal, hoping "that some or other that 

 travel into foreign parts may find this elegant plant, and know 

 it by this small expression, and bring it home with them, so that 

 we may come to a perfecter knowledge thereof." A few years 

 afterwards this wish was gratified. John Tradescant the younger 

 found the plant in Virginia, and succeeded in bringing it home 

 alive to England. It was also sent to Paris from Quebec by 

 Dr. Sarrazin, whose memory has been commemorated in the 

 name of the genus, by Tournefort. 



The first fact which was observed abiut the pitchers was, that 

 when they grew they contained water. But the next fact which 

 was recorded about them was curiously mythical. Perhaps 

 Morrison, who is responsible for it, had no favourable oppor- 

 tunites of studying them, for he declares them to b^, what is by 

 no means really the case, intolerant of cultivatim (rcspucre ciil- 

 tiiram vidcnlur). 



lie speaks of the lid, which in all the species is tolerably 

 riijidly fixed, as being furnished, by a special act of providence, 

 with a hinge. This idea was adopted by Linnxus, and some- 

 what amplified liy succeeding writers, who declared that in dry 

 weather the lid closed over the mouth, and checked the loss of 

 water by evaporation. Catesby, in his fine work on the Natural 

 History of Carolina, supposed that these water-receptacles might 

 " serve as an asylum or secure retreat for numerous insects, from 

 frogs and other animals whicli feed on them ;" — and others 

 folljwed Linn;eus in regarding the pitchers as reservoirs for 

 birds and other animals, more especially in times of drought ; 

 " priTliL't aquam sitienttbus aviciiUs." 



The superficial teleology of the last century was easily satisfied 

 without looking far for explanations, but it is just worth while 

 pausing for a moment to observe that, although Linnceus had no 

 malerials for making any real investigation as to the purpose of 

 the pitchers of Sarraceniis, he very sagaciously anticipated the 

 modern views as to their affinties. They are now regarded as 

 very near allies of water-Mies— precisely the position which 

 Linnaeus assigned to them in his fragmentary attempt at a true 

 natural classification. And besides this, he aho suggested the 

 analogy, which, improbable as it may seem at first sight, has 

 been worked out in detail by Baillon (in apparent ignorance of 

 Linna;u;' writings) between the leaves of Sarracenia and water- 

 lilies. 



Linnreus seems to have suppo-el that Sarracenia was originally 

 aquatic in its habits, that it had Nymphfea-like leaves, and that 

 when it took to a terrestrial life its leaves became hollo ved out, 

 to contain the water in which they could no longer float — in fact, 

 he shov.'ed himself to be an evolutionist of the true Darwinian 

 type. 



Catesby's suggestion was a very infelicitous one. The insscfs 

 which visit these plants may find in them a retrea'", but it is one 

 from which they never return. Linnaeus' correspondent Collin- 

 .son remarked in one of his letters, that "many poor insects 

 lose their lives by being drowned in these cisterns of water ;" 

 but William Bartram, the son of the botanist, seems to have 

 been the first to put on record, at the end of the last century, 

 the fact that Srrracenias catch insects and put them to death in 

 the whole ale way that they do. 



Befo-e stopping to consider how this is actually achieved, 

 I will carry the history a Utile further. 



In the two species in which the mouth is unprotected by the 

 lid it could not be doubted that a part, at any rate, of the con- 

 tained flui 1 was supplied by rain. But in Sarracenia varwlaris, 

 in which the lid closes over the mouth, so that lain cannot readily 

 enter it, there is no doubt that a fluid is secreted at the bottom 

 of the pitchers, which probably has a digestive function. 

 William Bartram, in the preface to his travels in 1791, described 

 this flui<l, but he was mistaken in supposing that it acted as a 

 lure. There is a sugary secretion which attracts insects, but 



