Book I. ANOMALIES OF VEGETABLE DEVELOPEMENT. 247 



known among the peasantry of Scotland by the name of witches' knots. They are occasioned, like the 



bunches of the stem, by some obstruction in the channel of the sap or proper juice. A peculiar sort of knot 



or bunch is also formed" on the branches of the dog-rose. The 



nucleus, which is generally from an inch to an inch and a half 



in diameter, is covered with a long and winged shag, first of a 



green and then of a purple colour, presenting the appearance 



of a small bunch of moss. (fig. 192.) It has been occasioned, 



like that of the stem of the thistle, by the puncture of an 



insect depositing its eggs in the tender shoot; for if it is cut« 



open about the month of August, it contains maggots. \ 



These anomalies remind us always of that singular disease in 



the human species, the Plica poloiiica. 



1603. The bud. The regular developement of 

 the hud is also often prevented hy means of the 

 puncture of insects, and converted into a large 

 glohular tumour. 



1604. The gall tumour is very often effected by a species of 

 Cynips, which drives its piercer into the heart of the bud while 

 vet tender, and penetrates with its saw into the very pith ; in. 

 jecting at the same time a drop of the corroding liquor con- 

 tained in its bag, and then laying its eggs. The bud being thus wounded, and the juices corrupted by 

 the injected poison, the circulation is not only impeded, but a fermentation is induced which burns the 

 contiguous parts and changes their colour. The extravasated juice flows round the egg, and is there accu- 

 mulated and converted into a sort of spongy lump, which vegetates and augments till it forms what is 

 called a gall. The gall thus formed affords both shelter and nourishment to the young maggot, which, 

 after being converted into a fly, pierces its enclosure and launches into the open air. The most remark- 

 able of such galls are those produced on the oak tree, and known in this country by the vulgar name of 

 oak-apples, (fig. 191. b) The bud of the willow, particularly .Salix //elix, is apt to be punctured by insects 

 and converted into a gall : but the conversion is not always complete ; and in this case the shoot remains 

 dwarfish, and the leaves, which are now protruded from nearly the same point, assume something of the 

 figure of a rose. Hence it has obtained the common name of the rose-willow. The galls of the Salvia 

 pomifera, formed in the above manner, are said to be of a very pleasant flavour, and are esteemed a 

 great delicacy in Eastern countries. 



1605. The leaves. These, like the buds, are also frequently chosen for the nidus of 

 insects, and disfigured with galls or excrescences. But the most remarkable gall 

 produced on the leaf, and indeed the most remarkable and important of all galls, 

 is that which is so extremely useful in the arts of dyeing and making ink, the nut-gall 

 of the shops. 



1606. The nut-gall is generated on the leaf of a species of oak that grows plentifully in the Levant, and 

 is so well known in commerce as to require no particular description. It is occasioned by the puncture of 

 the Cynips lyuercifblii, which deposits its egg in the substance of the leaf by making a small perforation 

 on the under surface. Galls and tumours are to be found on t lie leaves of many plants ; and indeed almost 

 all leaves are liable to deformities, giving them a blistered, wrinkled, or curled appearance, and often pro- 

 ducing disease. 



1607. The excess or deficiency of leaves protruded in a group sometimes constitutes the anomaly, as in 

 the case of the trefoils. 



1608. Sometimes it is found in the natural figure of the leaf itself, as in Asparagus officinalis, where 

 they are bristle-shaped ; Salsola Kali, awl-shaped ; and W'llium Cepa, in which they are tubular, tapering 

 to a point. But one of the most remarkable anomalies of figure is that which occurs in the genus Sar- 

 racem'rt, the lower portion of the leaves of which is tubular, ascending, and approaching to funnel-shaped, 

 or rather pitcher-shaped reversed, with a flattened and concave limb attached by the one side to the orifice 

 of the tube, and constituting the upper portion of the leaf. Linnaeus, who was acquainted with this 

 singularity of structure, accounted for it by supposing that it was an institution of Nature, meant for the 

 purpose of furnishing the plant with a supply of water, which it could thus catch and retain in the leaf: 

 but as some species of the genus do not readily admit water, notwithstanding their capacity to retain it, this 

 hypothesis is regarded by Sir J. E. Smith as being extremely doubtful, who accordingly offers a different 

 solution, founded upon the following facts. An insect, of the Sphex or /chneumon kind, had been observed 

 by one of the gardeners of the botanic garden at Liverpool to drag several large flies toa leaf of Sarracenwj 

 adunca, and to force them into the tubular part of it. On examination the leaf was found to be about half 

 rilled with water, in which the flies were now struggling ; the other leaves were also examined, and were 

 found crammed with dead or drowning flies. The leaves of Sarracem'a purpurea are said to exhibit also 

 the same phenomena, and seem peculiarly well adapted to entrap and confine flies, by having the margin 

 beset with inverted hairs, which render the escape of such insects as may have accidentally fallen into the 

 watery tube, or are intentionally forced into it, impracticable ; so that the putrid exhalation from the de;.d 

 insects contained in the leaf often offends the nostrils, even in passing near the plant. Hence Sir J. E. 

 Smith infers, that the growth of the plant is perhaps benefited by means of the air evolved by the dead 

 flies, which the water has been intended to tempt, and the leaves to entrap and retain. This ingenious 

 conjecture is, no doubt, sufficiently plausible as far as the plant may be affected ; but cannot be regarded 

 as quite satisfactory till such time as it shall have been shown that the health of the plant is injured when 

 insects are prevented from approaching it. 



1609. The Nepenthes distillatbria exhibits also an anomaly similar to that of Sarracem'a, in holding an 

 ounce or two of a fluid which appears to be secreted from the leaf, and to be intended as a lure to 

 insects, which gain admission either by the spontaneous opening of the lid, or by forcibly raising it them- 

 selves. The consequence is that they "fall into the fluid and aredrowned, no insect being capable of living 

 in it except a certain small squilla or shrimp, with a protuberant back, which, according to Rumphius, 

 sometimes crawls into it and can live there. To this phenomenon Sir J. E. Smith applies the same expli- 

 cation as above, which is of course liable to the same objection. 



1610. The figure of the leaf, however singular, is generally the same throughout the same individual, ex- 

 cept in the case of accidental deformity, and yet there are exceptions even to this rule ; for sometimes 

 the lower leaves of a plant are entire while the upper leaves are divided, as occurs in a variety of moun- 

 tainous plants, such as burnet, saxifrage, anise, coriander ; and sometimes the lower leaves ape divided 

 while the upper leaves are entire, as in the case of a variety of aquatics, particularly Ranunculus aquati- 

 cus, in which the lower leaves are capillary and immersed, and the upper leaves flat and circular, floating 

 on the surface of the water. But sometimes the dissimilitude of the leaves is still more remarkable: the 

 Chinese mulberry, a Botany Bay tree, has not two leaves alike in form on the whole plant. And, lastly, 

 there are some plants, as in the case of the Fungi, that arc who'ly destitute of leaves, and hence called 

 aphyllous; while there are others, as in the case of the .Fiici, that seem to be wholly leaf. 



1611. The flower. The principal anomaly of the flower is that by which one of its 



parts is unduly augmented, to the exclusion or diminution of some of the rest. The 



It 4 



