It is a little star-dust caught, a segment of the rainbow which I have clutched.
39) have jointed, flexible palps, feelers - often of excessive length - with a short basal segment, and the three terminal segments forming a club, and, in some genera, larvae with legs.
In many of those ants whose third abdominal segment forms a second " node," the basal dorsal region of the fourth segment is traversed by a large number of very fine transverse striations; over these the sharp hinder edge of the third segment can be scraped to and fro, and the result is a stridulating organ which gives rise to a note of very high pitch.
Apical cell, p. Wall marking limit between the plerome k, initial segment of root-cap. P and the pleriblem Pb.
In male beetles, however, the two pairs of genital processes (paramera) belonging to the ninth abdominal segment are always present, though sometimes reduced.
As in the Oligochaeta the peristomial segment is often without setae; but this character is not by any means so constant as in the Oligochaeta.
Turning to the thorax we find that the first segment (prothorax) is distinct and free, with a wide dorsal sclerite.
R, Optical section of leptoid (sieve-tube segment) of Phanerogam, with two proteid (companion) cells.
Antennal segment s form a distinct club.
In these ants the difference between the large, heavy, winged males and females, and the small, long-legged, active workers, is so great, that various forms of the same species have been often referred to distinct genera; in Eciton, for example, the female has a single petiolate abdominal segment, the worker two.
The prostomium overhangs the mouth, and is often of considerable size and, as a rule, quite distinct from the segment following, being A„ f s / 6/ ' A B I.
It is, however, always possible to recognize a head, which consists at least of the peristomial segment with a forward projection of the same, the prostomium.
Fielde show that an ant follows her own old track by a scent exercised by the tenth segment of the feeler, recognizes other inmates of her nest by a sense of smell resident in the eleventh segment, is guided to the eggs, maggots and pupae, which she has to tend, by sensation through the eighth and ninth segments, and appreciates the general smell of the nest itself by means of organs in the twelfth segment.
The female can protrude a long flexible tube in connexion with the eighth segment, carrying the sclerites of the ninth at its extremity, and these sclerites may carry short hairy processes A B D.yrnt,sc/'rle moathd ..
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.
In the latter case each segment of the solenostele frequently resembles a Dktyosteb.
In this use the term loses, of course, its morphoI logical value, and it is better to call such a segment of a broken-up I stele a meristele, the whole solenostele with overlapping leaf-gaps being called a dictyostele.
A tissue mother-cell of the xylem may, in the most advanced types of Dicotyledons, give rise to(I) a tracheid; (2) a segment of a vessel; (3) a xylem-fibre; or (4) a vertical file of xylem-parenchyma cells.
The insects of this order have mandibles adapted for biting, and two pairs of membranous wings are usually present; the first abdominal segment (propodeum) becomes closely associated with the fore-body (thorax), of which it appears to form a part.
The fourth abdominal segment is often very large, and forms the greater part of the hind-body; this segment is markedly constricted at its basal (forward) end, where it is embraced by the small third segment.
The young insect resembles its parent in most points, but the head is disproportionately large; the anterior abdominal spiracles are on the second segment instead of on the first, and the foot has only a single segment.
This consists of a few xylem elements, e a a segment of phloem, pericycle, and usually an arc of h~s endodermis, which closes round the bundle as it detaches ~
A tissue mother-cell of the phloem may give rise to (i) a segment of a sieve-tube with its companion cell or cells; (2) a phloem fibre; (3) a single phloem-parenchyma (cambiform) cell, or a ve~rtical file of short parenchyma cells.
- The Rhynchophora are a group of beetles easily recognized by the elongation of the head into a beak or snout, which carries the feelers at its sides and the jaws at its tip. The third tarsal segment is broad and bi-lobed, and the fourth is so small that the feet seem to be only four-segmented.
The head of an ant carries a pair of elbowed feelers, each consisting of a minute basal and an elongate second segment, forming the stalk or "scape," while from eight to eleven short segments make up the terminal "flagellum."
Biisgen that the sweet secretion (honey-dew) of the aphids is not derived, as generally believed, from the paired cornicles on the fifth abdominal segment, but from the intestine, whence it exudes in drops and is swallowed by the ants.
On the other hand, in certain Polychaeta the bundles of setae are so extensive that they nearly form a complete circle surrounding the body; and in the Oligochaet genus Perichaeta (=Pheretima), and some allies, there is actually a complete circle of setae in each segment broken only by minute gaps, one dorsal, the other ventral.
Oviducts of Oligochaeta, sperm ducts of Phreoryctes, the coelomoducts occupy, like the nephridia, two segments, the funnel opening into that in front of the segment which carries the external pore.
The more complete replacements, such as the nephridia of the genital segment of Tubifex by a subsequently formed genital duct, may be compared with the succession of the nesonephros to the pronephros in vertebrates, and of the metanephros to the mesonephros in the higher vertebrates..
The funnel, which is not large, appears to open, as a rule at least, into the segment in front of that which bears the external orifice.
In forehand play the bowl as it courses to the jack describes its segment of a circle on the right, in backhand play on the left.
The setae, which are always absent from the peristomial segment, are also sometimes absent from a greater number of the FIG.
The ventral region of the thoracic skeleton is complex, each segment usually possessing a median sternum with paired episterna (in front) and epimera (behind).
It is noteworthy that in this family only among the Polychaeta, the nephridia are not restricted to a single pair in each segment; so that the older view that the gonad ducts are metamorphosed nephridia is not at variance with the anatomical facts which have been just stated.
The genital ducts are limited to one segment (the 8th in Capitella capitata), and there are genital setae on this and the next FIG.
Though the paired arrangement of the nephridia is the prevalent one in the Chaetopoda, there are many examples, among the Oligochaeta, of species and genera in which there are several, even many, nephridia in each segment of the body, which may or may not be connected among themselves, but have in any case separate orifices on to the exterior.
- Diagrams of various Earth of several Geoscolicidae, the nephridiopores indicate the segments; to each segment corresponds internally a chamber of the coelom which is separated from adjacent segments by transverse septa,which are only unrecognizable in the genus Aeolosoma and in the head region of other Oligochaeta.
On the other hand, in most Oligochaeta the first segment has in the adult no nephridium, and in the case of Octochaetus the existence of a "head kidney" antedating the subsequently developed nephridia of the first and other segments has neither been seen nor proved to be absent.
It's a one-week tour, each day a separate segment, with everyone riding at their own pace—within reason.
When present they are either arranged in four bundles of from one to ten or even more setae, or are disposed in continuous lines completely encircling each segment of the body.
The former view has been extensively held, and it is supported by the fact that in Octochaetus the first segment of the body has a pair of nephridia which is exactly like those which follow, and, like them, persists.
C, Nuclear thread segment ing.
The conversion of the gravel road into a paved road made it much easier for riding bikes.
Nephridia generally paired, often very numerous in each segment, in the form of long, much-coiled tubes with intracellular lumen.