COCHLEOCTONUS COCOON. 



73 



the depth of full sixteen inches. The bottom should 

 be broken up either with spade, fork, or mattock. 

 On tliis, when duly levelled, two rows of set* are to 

 be placed six inches from each side of the trench, 

 which will leave a twelve-inch space between the 

 rows. The sets may be put six or eight inches apart 

 in the rows, and when the first trench is thus planted, 

 it is filled with the earth from the second, breaking it 

 well as it is thrown on the sets. The second trench 

 being thus opened, the bottom stirred, and planted 

 similar to the first, is filled with the earth from the 

 third, and so on to the end. 



The sets are inch-pieces of old roots. Some writers 

 advise the crowns only to be chosen ; these are cer- 

 tainly to be preferred, but any sound part of the root, 

 whether great or small, will do for sets. From each 

 set a single shoot is produced, and which after two 

 or three years' growth is fit for use. As the shoots 

 rise in rows one foot apart, they should be carefully 

 taken up one after another, beginning at the first. In 

 doing this it is usual to replant the vacant ground as 

 the digging up proceeds, so that the plantation may 

 be kept constantly furnished and productive ; for as 

 the spot chosen for the growth of horse-radish in 

 private gardens is always some bye corner of the 

 garden or orchard, it is seldom necessary to change 

 its place. 



Horse-radish may also be planted by a dibber of 

 sufficient size and length, after the ground is trenched. 

 The holes are made by line, and the sets dropped in, 

 pressed to the bottom, and covered with fine sifted 

 earth. Another mode of culture is by planting crowns 

 or sets in shallow trenches, and earthing up the plants 

 by covering them over eight inches deep in the win- 

 ters of the second and third years ; by this plan very 

 large stems are obtained. There is yet another 

 simpler method sometimes practised. The sets are 

 dibbed on the surface of prepared ground ; these 

 produce a strong descending root, which in the second 

 or third year is large enough for use. 



Horse-radish seldom produces perfect seeds, because 

 the principal energy of the plant is directed to enlarge 

 tlie root, it being a law of vegetation that when seeds 

 are produced plentifully the root is diminutive, and 

 vice versa. Planting may be done any time during 

 winter or spring ; and as the leaves do not appear till 

 near midsummer from deep planted sets of new plan- 

 tations, it is usual to take a spring crop of radish, 

 lettuce, or spinach, off the ground before the horse- 

 radish comes up. 



COCHLEOCTONUS (Meilzinsky). A genus 

 of coleopterous insects, belonging to the section 

 Pentamera, nearly allied Jo the glow-worm family 

 Lampyrida:, and established for the reception of the 

 large wingless and unwieldy females of the long pre- 

 viously established genus DRILUS, which see. 



COCHLOSPERMUM (Kunth). A genus of 

 lofty trees found in Mexico and India. Linnaean 

 class and order Monadclphia Polyandria, and natural 

 order Tcrnstrccmiaccae. Generic character: calyx 

 first in five parts, afterwards very much divided; 

 stamens inserted in the receptacle ; seed-vessel a 

 utriculus, containing one seed. These trees were 

 considered by Linnaeus and Willdenow to belong to 

 the genus Bombax, from the East Indian one pro- 

 ducing a substance like cotton, hence it received the 

 specific name of Gossipium. 



COCKCHAFFER. A common insect, bein 

 the Scarabacus melolontha of Linnaeus, or the Mc- 



lolontha vulgaris of modern authors. See MELO- 



LONTHID^E. 



COCKROACH. A well-known domestic, dis- 

 gusting insect, systematically distinguished under the 

 name of Blatta orientalis. Full details of its habits 

 will be found under the article BLATTIDA:. 



COCKS'-FOOT GRASS of agriculturists is the 

 Dactylis glorneratus of Linnaeus. It is a strong-grow- 

 ing British grass, and is always chosen as one of those 

 to be sown in forming permanent pastures. It is 

 next to the rye-grass for earliness, and having strong 

 roots, produces a thick tuft of succulent leaves, very 

 suitable for early lambs. 



COCKSPUR THORN is the Cratcegus cnugaUi 

 of Linnaeus. It is a North American plant, and has 

 long been cultivated in this country as a shrubbery 

 ornament. There are four or five varieties ii- nurse- 

 ries, and, like all the genus, admired for their snowy 

 blossoms in May. They are mostly propagated in 

 this country by grafting on the common whitethorn. 



COCOON. The envelope of silken or other 

 materials, formed by the larvae of many insects, im- 

 mediately previous to their assuming the pupa or 

 chrysalis state. Perhaps in no department of our 

 knowledge of the lower tribes of animals, is there so 

 much skill, or so much of that faculty which we term 

 instinct displayed, as in the proceedings which cha- 

 racterise the formation of these envelopes. All 

 larvre, however, do not make these coverings, the 

 cause of which is at once obvious ; the pupa of the 

 grasshopper or cockroach, dragon-fly or cimex, is an 

 active animal, continuing to enjoy all the habits of 

 the larva?, and consequently not needing any other 

 defence than it possessed in its former state, but in 

 other insects the case is entirely different ; the pupa 

 state being one of inactivity and total helplessness, 

 and in which the insect is consequently subject to 

 the attacks of any stray bird or mouse, or not less 

 voracious insect, which would feast with as much 

 avidity upon the soft and creamy substance of the 

 newly formed chrysalis, as the Romans did upon the 

 cossus, which was a large insect in the earlier stage, 

 and which is considered to have been the larva of 

 the goat moth (Cossus tigmperda). Hence the neces- 

 sity, not only for retreat to some quiet and unobserved 

 corner or hole, but also for a covering for more com- 

 plete concealment and defence. At this time many larvae 

 accordingly make their way several inches deep into 

 the earth. Here, or concealed under leaves, moss, 

 or other like matter, many insects become pupae, with 

 the mere precaution of fastening the substances which 

 conceal them together with a glutinous secretion from 

 the mouth ; but others are far more careful, forming 

 for themselves an entire covering, composed either 

 of silk spun from their own mouths, or of silk united 

 with the adjacent materials. Some few larvae, how- 

 ever, as those of the ant-lion (Myrmclcon), and the 

 lace-winged aphidivorous flies (Hemerobiiis), have the 

 spinning apparatus placed at the extremity of the 

 body. 



Some cocoons are formed simply of a few threads, 

 spun into an open work case, which permits the in- 

 closed insect to be plainly perceived through the 

 meshes ; this is the case with the gipsy and satin 

 moths (Hypogymna dispar and Leucoma salicis), &c. 

 Such is also the case with the cocoons of some of the 

 weevils and chrysomelidous beetles. The cream 

 spotted tiger-rnoth (Arctia villica, see vol. i. p. 550), 

 is more careful, forming a much closer cocoon, but 



