The head - carrying feelers, mandibles and two pairs of maxillae - is succeeded by the three thoracic segments, each bearing a pair of strong five-segmented legs, whose feet, like those of the adult, carry two claws.
As many as 162 segments in eight groups are practically used.
0, Optical section of two adjacent leptoids (sieve-tube segments) of Pteridophyte, with sieve plates (s.
Q, Three segments of a pitted vessel of Phanerogam.
It always consists of true parenchyma, and is entirely formed by the cutting off of segments from an apical cell.
Haplostele, the segments of inner endodermis, pericycle, phloem and ~ Pig.
I mesocycle joining with the corresponding outer segments to form a nearly concentric structure.
In the stem, segments are successively cut off from the sides of the tetrahedron, and b~ their subsequent division the body of the stem is produced.
Segments are then cut if from the outer sides of these initial cells.
The protoxylem and protophloem are developed a few cells from the inner and outer margins respectively of the desmogen strand, the desmogenic tissue left over giving rise to the segments of endocycle and pericycle capping the bundle.
For instance, the difference between the long-stalked and finely-cut leaves of Anemone attacked with rust and the normal leaves with broad segments, or between the urceolate leaves occasionally found on cabbages and the ordinary formin these cases undoubtedly pathological and teratological respectivelyis nothing like so great as between the upper and lower normalleaves of many Umhelliferae or the submerged and floating leaves of an aquatic Ranunculus or Cabomba.
The reduction is brought about simply by the segmentation of the spirem thread into half the number of segments instead of the normal number.
The segments of each ch~omosome are usually twisted upon.
Cambricum (originally found in Wales) has the pinnae themselves deeply cut into narrow segments; var.
2 b, 9b and 26 b, c); the number of segments is usually eleven, but may vary from two to more than twenty.
1, A) are of the usual insectan type, but in many families one, two, or even three of the five foot-segments may be reduced or absent.
The ninth and tenth segments are at most times retracted within the eighth.
Ten segments can be distinguished in the tapering abdomen, the ninth frequently bearing a pair of tail-feelers (cerci), and the tenth, attached ventrally to the ninth, having the anal opening at its extremity and performing the function of a posterior limb, supporting and temporarily fixing the tail end of the insect on the surface over which it crawls.
In a large number of beetles of different families, stridulating areas occur on various segments of the abdomen, and are scraped by the elytra.
Such obvious features as the number of segments in the foot and the shape of the feeler were used by the early entomologists for distinguishing the great groups of beetles.
The arrangement dependent on the number of tarsal segments - the order being divided into tribes Pentamera, Tetramera, Heteromera and Trimera - was suggested by E.
Ganglbauer (1892) divides the whole order into two sub-orders only, the Caraboidea (the Adephaga of Sharp and the older writers) and the Cantharidoidea (including all other beetles), since the larvae of Caraboidea have five-segmented, two-clawed legs, while those of all other beetles have legs with four segments and a single claw.
2) are Adephaga highly specialized for life in the water, the hind-legs having the segments short, broad and fringed, so as to be well adapted for swimming, and the feet without claws.
The fore-legs of many male dyticids have the three proximal foot-segments broad and saucer-shaped, and covered with suckers, by means of which they secure a firm hold of their mates.
Mandibles being well adapted for the capture of small insect-victims. The larvae are more specialized than those of other Adephaga, the head and prothorax being very large and broad, the succeeding segments slender and incompletely chitinized.
The number of antennal segments varies from eleven to two.
With very few exceptions, the larva in this group is active and campodeiform, with cerci and elongate legs as in the Adephaga, but the leg has only four segments and one claw.
These segments are very mobile, and as the rove-beetles run along they often curl the abdomen upwards and forwards like the tail of a scorpion.
This is a somewhat heterogeneous group, most of whose members are characterized by clubbed feelers and simple, unbroadened tarsal segments - usually five on each foot - but in some familie andenera the males have less than the normal number on the feet of one pair.
The bestknown family is the Hydrophilidae, in which the feelers are short with less than eleven segments and the maxillary palpi very long.
Side, being scooped in bubbles by the terminal segments of the feelers when the insect rises to the surface.
The beetles have feelers with eleven segments, whereof the terminal few are thickened so as to form a club.
From this point backwards the successive abdominal segments, as far as the seventh or eighth, can be readily made out.
Ten segments can be recognized - according to the studies of K.
The general graphy, principle Arms a and arrangement b, one at eachstation and d B, are connected to the line wire, and are made to rotate simultaneously over metallic segments, 3, 4, and I', 3', 4', at the two stations, so that when the arm a is on segment i at A, then b is on segment I' at B, and so on.
At each station sets of telegraph apparatus are connected to the segments, so that when the arms are kept rotating the set connected to I becomes periodically connected to the set connected to I', the set connected to 2 to the set connected to 2', and so on.
In practice the number of segments actually employed is much greater than that indicated on the figure, and the segments are arranged in a number of groups, as shown by fig.
27, all the segments i being connected together, all the segmen t s 2, all the segments 3, and all the segments 4.
In practice this subdivision of the segments is so far extended that the intervals of disconnexion become extremely A Line- ----- 2/ -- f?
The arm which moves round over the segments rotates at the rate of three revolutions per second, and is kept in motion by means of an iron toothed wheel, the rim of which is set in close proximity to the poles of an electromagnet.
- Grouping of Segments in Multiplex System.
The newly hatched insect closely resembles the parent, and the wing-rudiments appear externally on the second and third thoracic segments; but before the final moult the nymph remains quiescent, taking no food.