Each bud produced FIG.
As medusae are known to bud medusae from the radial canals there is nothing impossible in Aliman's theory, but it cannot be said to have; received satisfactory proof.
I., II., III., vomitories) the imaginal disks are to all the three thoracic segments appearance completely separated from of the larva; I, 2, 3, buds the hypodermis, with which they are, of the legs of the imago; la, however, really organically connected bud of head-lobes; f, of by strings or pedicels.
There was the customary group of tourists with names like Bud and Ethel and Elmer and Clara— names not assigned to anyone born after World War II.
F, foundersecond bud, which usually polyp; I, 2, 3, succession of polyps forms a side branch or pinnule budded from the founder.
Or a polyp on the main stem, after having budded a second time to form a pinnule, may give rise to a third bud, which starts a new biserial FIG.
Polyp 7 has proof sense, 1 o c oduced as its first bud, 8; as its second bud, a7, motion and nutriwhich starts a uniserial pinnule; and as a third t i on, until its bud I', which starts a biserial branch (I I'-VI') medusoid nature that repeats the structure of the main stem and and organization gives off pinnules.
It is marked by the formation in the bud of a characteristic structure termed the entocodon (Knospenkern, Glockenkern).
It should be remembered that a single complete defoliation of a herbaceous annual may so incapacitate the assimilation that no stores are available for seeds, tubers, &c., for another year, or at most so little that feeble plants only come up. In the case of a tree matters run somewhat differently; most large trees in full foliage have far more assimilatory surface than is immediately necessary, and if the injury is confined to a single year it may be a small event in the life of the tree, but if repeated the cambium, bud-stores and fruiting may all suffer.
Fortunately, however, the government, by dismissing the ringleader, Dr Campanozzi, in time nipped the agitation in the bud, and it did attempt to redress some of the genuine grievances.
(From Lubbock, after Allman.) by the founder proceeds to grow and to bud in the same way as the founder did, producing a side branch of the main stem.
In the sympodial method of budding, on the other hand, the founder-polyp is of limited growth, and forms a bud from its side, which is also of limited growth, and forms a bud in its turn, and so on (figs.
The polyp may then form a second bud, which becomes the starting point of a new system, the beginning, that is, of a new branch; and even a third bud, starting yet another system, may be produced from the same polyp. Hence the colonies of Calyptoblastea may be com plexly branched, and the bud ding may be biserial through out, uniserial throughout, or partly one, partly the other.
And, lastly, if the bud m, Manubrium.
Finally, a mouth is formed by breaking through at the apex of the manubrium, and the now fully-formed medusa becomes separated by rupture of the stalk of the bud and swims away.
If the bud, however, is destined to give rise not to a free medusa, but to a gonophore, the development is similar but becomes arrested at various points, according to the degree to which the gonophore is degenerate.
It is seen from the foregoing account of medusa - budding that the entocodon is a very important constituent of the bud, furnishing some of the most essential portions of the medusa; its cavity becomes the subumbral cavity, and its lining furnishes the ectodermal epithelium of the manubrium and of the sub-umbral cavity as far as the edge of the velum.
The entocodon, however developed, gives rise at first to a closed cavity, representing a closing over of the umbrella, temporary in the bud destined to be a free medusa, but usually permanent in the sessile gonophore.
Each bud arises as a thickening of the epithelium, which.
When the bud is nearly complete, the body-wall of the parent immediately below it becomes perforated, placing the coelenteric cavity of the parent in secondary communication with that of the bud (H), doubtless for the better nutrition of the latter.
(After C. Chun.) A, The epithelium becomes twothe bud forms an entocodon layered.
Secondly, there is the evidence from the development, namely, the presence of the entocodon in the medusa-bud, a structure which, as explained above, can only be accounted for satisfactorily by derivation from a medusan type of organization.
In some cases, any polyp of the colony may bud medusae; in other cases, only certain polyps, the blastostyles, have this power.
In B the spadix of the upper bud has protruded itself through the top of the gonoat the base of the theca and the acrocyst (ac) is secreted round it.
In some cases the buds do not become detached at once, but the stolon continues to grow and to produce more buds, forming a " bud-spike " (Knospencihre), which consists of the axial stolon bearing medusa-buds in all stages of development.
In their most primitive form they are seen in Velella as " gonosiphons," which possess mouths like the ordinary sterile siphons and bud free medusae.
An opening to the exterior S From a comparison of the two embryological types there can be no doubt on two points; first, that the pneumatophore and the protocodon are strictly homologous, and, therefore if the nectocalyx is comparable to the umbrella of a medusa, as seems obvious, the pneumatophore must be so too; secondly, that the coenosarcal axis arises from the ex-umbrella of the medusa and cannot be compared to a manubrium, but is strictly comparable to the " bud-spike " of a Narcomedusan.
Woltereck considers the siphonophores most nearly allied to the Narcomedusae, producing like the buds from an aboral stolon, the first bud being represented by the pneumatophore or protocodon, in different cases.
Metamorphosis.It has already been pointed out that each kind of member of the body may present a variety of forms. For example, a stem may be a tree-trunk, or a twining stem, or a tendril, or a thorn, or a creeping rhizome, or a tuber; a leaf may be a green foliage-leaf, or a scale protecting a bud, or a tendril, or a pitcher, or a floral leaf, either sepal, petal, stamen or carpel (sporophyll); a root may be a fibrous root, or a swollen tap-root like that of the beet or the turnip. All these various forms are organs discharging some special function, and are examples of what Wolff called modification, and Goethe metamorphosis.
The sepals are generally organs for the protection of the flower-bud; the petals, for attracting insects by their conspicuous form and color; the foliage-leaves, for the assimilation of carbon dioxide and other associated functions.
Similarly bud-scales can be caused to develop into foliage-leaves, if the buds to which they belong are caused to grow out in the year of, their formation by the removal of the existing foliage-leaves.
However, it may still be useful in describing monstrosities, and perhaps also those cases in which an organ serves first one purpose and then another, as when a leafy shoot eventually becomes a thorn, or the base of a foliage-leaf becomes a bud-scale.
The stipules of the leaves act as protecting scale-leaves in the winter-bud and fall when the bud opens in spring.
The body-cavity and the muscular, fibrous and vascular tissues are traced partly to two symmetrically disposed " mesoblasts," which bud off from the invaginated arch-enteron, partly to cells derived from the ectoderm, which at a very early stage is connected by long processes with the invaginated endoderm.
The change that is required to transform Exopterygota into Endopterygota is merely that a cell of hypodeimis should proliferate inwards instead of outwards, or that a minute hypodermal evaginated bud should be forced to the interior of the body by the pressure of a contracted cuticle.
(Cattle food.) The adult weevils puncture the young flower-buds and deposit eggs; and as the grubs from the eggs develop, the bud drops.
Examination showed that although the weevil attacked the young buds these did not drop off, but that a special growth of tissue inside the bud frequently killed the grub.
Spes is represented as a beautiful maiden in a long light robe, lifting up her skirt with her left hand, and carrying in her right a bud already closed or about to open.
BdXXo, a green bud, on account of a brilliant green line in its spectrum) in the selenious mud of the sulphuric acid manufacture; the chemical affinities of this element, on the one hand approximating to the metals of the alkalis, and on the other hand to lead, were mainly established by C. A.
At the same time there is often a change in colour in the flowers, which are red in bud, becoming blue as they expand, as in Myosotis, Echium, Symphytum and others.
As to the nectarine, of its origin as a variation from the peach there is abundant evidence, as has already been mentioned; it is only requisite to add the very important fact that the seeds of the nectarine, even when that nectarine has been produced by bud-variation from a peach, will generally produce nectarines, or, as gardeners say, "come true."
In well-developed shoots the buds are generally double, or rather triple, a wood bud growing between two fruit buds; the shoot must be cut back to one of these, or else to a wood bud alone, so that a young shoot may be produced to draw up the sap beyond the fruit, this being generally desirable to secure its proper swelling.
On some of the bushes might be seen a bud, a blossom, a baby, a half-grown person and a ripe one; but even those ready to pluck were motionless and silent, as if devoid of life.
I have felt a bud "shyly doff her green hood and blossom with a silken burst of sound," while the icy fingers of the snow beat against the window-panes.
What mysterious force guided the seedling from the dark earth up to the light, through leaf and stem and bud, to glorious fulfilment in the perfect flower?
I used to start them in the open land also, where they had come out of the woods at sunset to "bud" the wild apple trees.
In the case of the great grey kangaroo, for instance, the period of gestation is less than forty days, and the newly-born embryo, which is blind, naked, and unable to use its bud-like limbs, is little more than an inch in length.
The direct method of medusa-budding only differs from the polyp-bud by its greater complexity of parts and organs.
The entocodon is usually formed, proving the medusoid nature of the bud, but in sporosacs the entocodon may be rudimentary or absent altogether.
The tissues of the bud become differentiated into ectoderm and endoderm, and the endoderm of the bud becomes secondarily continuous with that of the parent, but no part of the parental endoderm contributes to the building up of the daughter-polyp. Lang regarded this method of budding as universal in polyps, a notion disproved by O.
The embryo consists of an axis bearing one (Monocotyledons) or two (Dicotyledons) cotyledons, which protect the stem bud (plumule) of the future plant, and ending below in a radicle.