206 



ARTICULATA. 



which also bear smaller heads : and these when no 

 larger than a hen's egg are useful in the kitchen. 

 In gathering the principal heads for use, they should 

 not be cut, but wrenched or twisted off; by which 

 many of the strong fibres of the stem which pene- 

 trate into the bottom are withdrawn, thereby improv- 

 ing the quality of the latter when brought to table. 

 The stems may be cut down as soon as the flowers 

 are off. 



There are two kinds of artichoke in cultivation, 

 viz., the green globe, which is the largest, and the 

 purple globe, which is said to be more delicate and 

 superior in flavour. Either seeds or roots may be 

 purchased at the seedsmen's shops. 



A plantation of artichokes, if properly planted at 

 first, and receiving a dressing of good dung every third 

 or fourth year, deeply digged in among the roots, 

 with careful treatment at the spring dressing, and 

 well secured from frost in winter, will continue pro- 

 ductive for a considerable period say ten or twelve 

 years. When a plant is four or five years old, how- 

 ever, it is then at its best. 



ARTICULATA jointed animals. The third 

 of the grand divisions into which Cuvier arranges the 

 animal kingdom, and the second of the inverte- 

 brated or spineless animals. The species which it 

 comprehends are exceedingly numerous and varied' 

 in their forms and their habits and economy, so 

 that they not only extend to genera, groups, and 

 orders, but admit of division into four classes 

 Annellida, Crustacea, Arachnids, and Imccta, all 

 of which have their characters as classes as well 

 defined as those of the four classes of vertebrated 

 animals Mammalia, Birds, Reptiles, and Fishes. 

 But as these, in all their classes, and in all the varie- 

 ties of each class, preserve the fundamental characters 

 of the grand division the articulated spine and the 

 other parts of the internal bony skeleton, which gives 

 form and support to their bodies, and affords points of 

 rest, centres of motion, and levers, by means of 

 which the muscles or organs of motion are enabled 

 to act ; so the Articulata, destitute in every instance 

 of even the slightest vestige of spine or internal 

 skeleton, preserve their fundamental character of a 

 jointed external covering, which in like manner deter- 

 mines their shape, and gives insertion to their organs 

 of motion. In the majority of cases, they are, like 

 the vertebrated animals, furnished with distinct organs 

 of locomotion ; with feet, with wings, or with fins (or 

 at least with organs which answer the same purpose), 

 according to the element in, or on, which they move ; 

 but there are some which are destitute of such organs, 

 and these crawl or wriggle along by the help of the 

 edges of their rings, or by the flexures of their bodies. 

 Some of the apodal, or footless articulata, as the com- 

 mon earth worm and the leech, appear indeed to 

 derive advantages in their locomotion from the want 

 of an internal spine. Spined animals cannot lengthen 

 their bodies beyond the length of the spine stretched 

 to a straight line ; and they cannot shorten them in 

 any way but by bendings or flexures of that organ 

 at least the changes that can be made in either way 

 are so trifling, that they are not worthy of taking 

 into account. The spine, though it has its advan- 

 tages, has thus, also, its disadvantages. Its contents, 

 the continuation of the nervous mass, are too 

 essential to the life of the animal, for admitting of 

 alterations by lengthening and thickenings by con- 

 traction, as these would disturb, or possibly suspend 



the functions of those nerves which, originating in the 

 contents of the spine, are essential to the motions of 

 the animal. But the articulated covering of tho 

 animals under consideration, has no immediate con- 

 nexion with their nervous mass ; and so when neces- 

 sary to the habits of the animal, lengthenings and 

 shortenings of the body, by expansions and con- 

 tractions of the spaces between the rings, may take 

 place without any interruption or injury to the 

 sentient system. When this takes place to a large 

 extent, the rings themselves vary in breadth and 

 diameter, widening and becoming smaller when the 

 animal stretches itself, and narrowing and expanding 

 in diameter when it shortens. Thus we see that 

 every varied structure of the animal frame has its 

 peculiar advantages ; so that, however different they 

 may be from each other, we cannot, when we take 

 into consideration the functions which they have to 

 perform, say that one is better than another. 



This lengthening and shortening of the body are 

 required only in those species which have not feet, 

 and they are confined to certain species of the annel- 

 Iida3. The other orders of articulated animals have 

 feet, and have them articulated, or jointed, as well as 

 the vertebrated animals. The only difference, except 

 number, size, and form, are not merely similar to the 

 characteristic distinction of the grand division, but 

 actually part of it. The articulations of the legs are 

 in the covering, and the muscles and all the other 

 organs are within ; and though there are in some, as 

 in certain joints of the large lacs of crabs, inter- 

 nal substances of a bony, or rather cartilaginous 

 nature, which in part support the muscles, there are 

 not, in any degree, approximations to an internal 

 skeleton : they are appendages to the external crust, 

 and articulated to that, and to that only. 



When we attentively consider legs of this con- 

 struction, we find that they possess many valuable 

 qualities which cannot be possessed by legs with 

 internal bones, and the muscles and other soft parts 

 on the outside. The external crust is stronger, or, 

 at all events, stiffer than the same quantity of matter 

 in a solid bone, upon the same principle that a hollow 

 cylinder of metal is stronger or stiffer than a solid 

 rod containing the same quantity in an equal length ; 

 and the strength is very generally augmented by the 

 different articulated pieces being spindle-shaped, or 

 thicker in the middle than at the ends, and having 

 the longitudinal outlines curved. By this means every 

 part of the surface resists pressure like an arch. 



It is also easy to see that, shielded as they are in 

 the crust, or other firm articulated covering, the soft 

 parts are far more safe from injury than if they were' 

 external, with the bone inside, against which they 

 might be pressed, and nothing to defend them but 

 the soft integuments. The leg of the articulata thus 

 bears something like the same relation to that of the 

 vertebrated animals, as a leg clad in armour bears to a 

 leg which is naked ; only the advantage is greater, 

 because the soft parts of a mailed leg, when pressed 

 by dinting the mail, are resisted and crushed mid- 

 way by the bone ; whereas those in the articulata are 

 resisted only at the opposite surface; and as the 

 pressure there is, as it were, against the under or con- 

 cave side of the arch, it has a tendency to give way 

 a little, and by its elasticity take off much of the 

 injury of the crush. In consequence of this structure 

 it is demonstrable, upon the most simple and obvious 

 principles of mechanics, that the limbs of the articu- 



