Word Finder - spores

definition

A reproductive particle, usually a single cell, released by a fungus, alga, or plant that may germinate into another.

definition

A thick resistant particle produced by a bacterium or protist to survive in harsh or unfavorable conditions.

definition

To produce spores.

Such applications at the momelit when spores are germinating on the leaves, e.g.

The danger from this source is remote, as the microbe does not form spores within the animal body.

The primary function of the flower is to bear the spores.

In most cases four spores are formed within the cell by free formation.

In the Thallophytes the cytoplasm may be segmented by constriction, due to the in-growth of a new cell wall from the old one, as in Spirogyra and Cladophora, or by the formation of cleavage furrows in which the new cell-wall is secreted, as occurs in the formation of the spores in many Algae and Fungi.

Accepting this view of the phylogeny of the leaf, the perianthleaves (sepals and petals) and the foliage-leaves may be regarded as modified or metamorphosed sporophylls; that is, as leaves which are adapted to functions other than the bearing of spores.

Gymnosporangium sabinae, one of the rusts (Uredineae) passes one stage of its life-history on living pear leaves, forming large raised spots or patches which are at first yellow but soon become red and are visible on both faces; on the lower face of each patch is a group of cluster-cups or aecidia containing spores which escape when ripe.

This stage in the life-history was formerly regarded as a distinct fungus with the name Roestelia cancellata; it is now known, however, that the spores germinate on young juniper leaves, in which they give rise to this other stage in the plant's history known as Gymnosporangium.

The gelatinous, generally reddish-brown masses of spores - the teleutospores - formed on the juniper in the spring germinate and form minute spores - sporidia - which give rise to the aecidium stage on the pear.

The fungus mycelium grows between the cuticle and the epidermis, the former being ultimately ruptured by numerous short branches bearing spores (conidia) by means of which the disease is spread.

Pear trees may 2, Section of leaf surface showing the also be attacked by a great spores or conidia, c, borne on long variety of insect pests.

The presence of the volva, and the clear white gills and spores, distinguish this genus from all other agarics.

Ascus from perithecium containing six spores, X30o.

These are minute, oval, colourless spores, which serve to spread the disease over the vineyard and from place to place.

Single ascus, more enlarged, showing the eight contained spores.

Cercospora Vitis (Cladosporium viticolum), which has club-shaped spores of a green-brown colour, also attacks the leaves; but, unless the season is extremely unfavourable, it does little harm.

The latter is the more serious, as in addition to the actual damage done by the beetle the holes afford entrance to fungus spores, &c. Under the name " horn worms " are included the larvae or caterpillars of species of Protoparce.

In cannel coals the prevailing constituents are the spores of cryptogamic plants, algae being rare or in many cases absent.

In addition, the great majority have also another method of reproduction, for increasing the number of the parasites in any individual host; this is distinguished as multiplicative or endogenous reproduction, from the propagative or exogenous method (by means of the resistant spores), which serves for the infection of fresh hosts and secures the dissemination and survival of the species.

The spores formed on the delicate grey mould are carried during the summer from one plant to another, thus spreading the disease, and also germinate in the soil where the fungus may remain passive during the winter producing a new crop of spores next spring, or sometimes attacking the scales of the bulbs forming small black hard bodies embedded in the flesh.

This prevents infection from outside and also destroys any spores or fungus mycelium that may have been packed away along with the bulbs.

Only a single pathogenic species can withstand the short boiling to which milk is ordinarily treated in domestic management, and this is the anthrax bacillus containing spores.

The spores germinate on a damp surface and enter the cortex through small cracks or wounds in the protecting layer.

The algal cells are never known to form spores while part of the lichen-thallus, but they may do so when separated from it and growing free.

The soredia are the most successful method of reproduction in lichens, for not only are some forms nearly always without spore-formation and in others the spores laregly abortive, but in all cases the spore represents only the fungal component of the thallus, and its success in the development of a new lichen-thallus depends on the chance meeting, at the time of germination, with the appropriate algal component.

The spores themselves may be unicellular without a septum or multicellular with one or more septa.

At other times the spores are divided by both transverse and longitudinal septa producing the muriform (murali-divided) spore so called from the resemblance of the individual chambers to the stones in a wall.

The very large single spores of Pertusaria have been shown to contain numerous nuclei and when they germinate develop a large number of germ tubes.

The spores are ejected from the apothecia and peri thecia as in the fungi by forcible ejacu lation from the asci.

When the spores are thrown out some of these hymenial gonidia, as they are called, are carried with them.

When the spores germinate the germ-tubes surround the algal cells, which now increase in size and become the normal gonidia of the thallus.

A solution of iodine is also used as a test owing to the blue or wine-red colour which the thallus, hymenium or spores may give with this reagent.

The paraphyses branch and form a network (capillitium) over the asci, the capillitium and ejected spores forming a long persistent powdery mass (mazaedium).

Spores usually two-celled, either with a strongly thickened cross-wall often perforated by a narrow canal or with crosswall only slightly thickened.

In the first case the spores are usually colourless, the second case always brown.

The spores should be sown in well-drained pots or seed pans on the surface of a mixture of fibrous sifted peat and small broken crocks or sandstone; this soil should be firmly pressed and well-watered, and the spores scattered over it, and at once covered with propagating glasses or pieces of sheet glass, to prevent water or dry air getting to the surface.

The spores may be sown as soon as ripe, and when the young plants can be handled, or rather can be lifted with the end of a pointed flat stick, they should be pricked out into well-drained pots or pans filled with similar soil and should be kept moist and shady.

Spores may be sown as above described, but in a much lower temperature.

The reproductive spores are borne in sacs (asci) which form a dense layer on the surface, appearing like a bloom in July; they are scattered by the wind and propagate the disease.

The reproductive spores are formed in embedded flesh-shaped receptacles (perithecia) and scattered after the leaves have fallen.

The spores, which may be unior multi-cellular, are either abstricted free from the ends of hyphae (acrogenous), or formed from segments in their course (chlamydospores) or from protoplasm in their interior (endogenous).

It was formerly the custom to include with the Fungi the Schizomycetes or Bacteria, and the Myxomycetes or Mycetozoa; but the peculiar mode of growth and division, the cilia, spores and other peculiarities of the former, and the emission of naked amoeboid masses of protoplasm, which creep and fuse to streaming plasmodia, with special modes of nutrition and spore-formation of the latter, have led to their separation as groups of organisms independent of the true Fungi.

As with other plants, so in fungi the essential process of fertilization consists in the fusion of two nuclei, but owing to the absence of well-marked sexual organs from many fungi, a peculiar interest attaches to certain nuclear fusions in the vegetative cells or in young spores of many forms. Thus in Ustilagineae the chlamydospores, and in Uredineae the teleutospores, each contain two nuclei when young, which fuse as the spores mature.

Morphologically considered, spores are marked by peculiarities of form, size, colour, place of origin, definiteness in number, mode of preparation, and so forth, such that they can be distinguished more or less sharply from the hyphae which produce them.

The only physiological peculiarity exhibited in common by all spores is that they germinate and initiate the production of a new fungus-plant.

Whether a spore results from the sexual union of two similar gametes (zygospore) or from the fertilization of an egg-cell by the protoplasm of a male organ (oospore); or is developed asexually as a motile (zoospore) or a quiescent body cut off from a hypha (conidium) or developed along its course (oidium or chlamydospore), or in its protoplasm (endospore), are matters of importance which have their uses in the classification and terminology of spores, though in many respects they are largely of academic interest.

In practice these various kinds of spores of fungi receive further special names in the separate groups, and names, more over, which will appear, to those unacquainted with the history, to have been given without any consistency or regard to general principles; nevertheless, for ordi nary purposes these names are far more useful in most cases, owing to their descriptive character, than the proposed new names, which have been only partially accepted.

Other series of modifications arise in which the tissues corresponding to the stroma invest the sporogenous hyphal ends, and thus enclose the spores, asci, basidia, &c., in a cavity.

Another simple case is where the plane or slightly convex surface of the stroma rises at its margins and overgrows the sporogenous hyphal ends, so that the spores, asci, &c., come to lie in the depression of a cavity - e.g.

In such examples as the above we may regard the hymenium (Solenia, Cyphella), zygospores, or asci as truly invested by later growth, but in the vast majority of cases the processes which result in the enclosure of the spores, asci, &c., in a "fructification" are much more involved, inasmuch as the latter is developed in the interior of hyphal tissues, which are by no means obviously homologous with a stroma.