When the tuber of a potato begins to germinate the shoots which it puts out derive their food from the accumulated store of nutritive material which has been laid up in the cells of the tuber.
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.
Allowing for those which fail to germinate (perhaps 25%), loss in transplanting, weak and backward plants, &c., one ounce of seed should yield about 40,000 plants.
Amid such conditions the idea of railways would have been slow to germinate had not a catastrophe furnished some impetus.
It is essential that the grains on the maltster's floor should germinate simultaneously, hence at the time of reaping, the whole crop must be as nearly as possible in the same stage of maturity.
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.
The lactic acid bacillus, always present in unboiled milk (to which the souring of milk is due), is easily destroyed by heat; but the bacillus mesentericus, often found in it, forms spores, which are not destroyed by ordinary boiling, and germinate when the milk is kept at a moderately warm temperature, producing a brisk fermentation whereby a large volume of gas is liberated.
During the middle of the 2nd century a number of varying christological views began to germinate, growing for a time side by side.
The spores germinate on a damp surface and enter the cortex through small cracks or wounds in the protecting layer.
The disease is peculiarly contagious and infectious, owing to the development of the fungus through the skin, whence spores are freed, which, coming in contact with healthy caterpillars, fasten on them and germinate inwards, giving off corpuscles within the body of the insect.
In favour of the conidial view is the fact that in the case of Collema and a few other forms the spermatia have been made to germinate in artificial cultures, and in the case of Calicium parietinum Moller succeeded in producing a spermogonia bearing thallus from a spermatium.
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.
When the spores germinate the germ-tubes surround the algal cells, which now increase in size and become the normal gonidia of the thallus.
The only physiological peculiarity exhibited in common by all spores is that they germinate and initiate the production of a new fungus-plant.
They are characterized especially by the zygospores, but the asexual organs (sporangia) exhibit interesting series of changes, beginning with the typical sporangium of Mucor containing numerous endospores, passing to cases where, as in Thamnidium, these are accompanied with more numerous small sporangia (sporangioles) containing few spores, and thence to Chaetocladium and Piptocephalis, where the sporangioles form but one spore and fall and germinate as a whole; that is to say, the monosporous sporangium has become a conidium, and Brefeld regarded these and similar series of changes as explaining the relation of ascus to conidium in higher fungi.
The conidia are fragrant and are carried by bees to the stigma of the bilberry; here they germinate with the pollen and the hyphae pass with the pollen tubes down the style; the former infect the ovules and produce sclerotia, therein reducing the fruits to a mummified condition.
In lepto and micro forms both aecidiospores and uredospores are absent, the sporidia producing a mycelium which gives rise directly to teleutospores; in the lepto forms the teleutospores can germinate directly, in the micro forms only after a period of rest.
An epiphytic fungus is not necessarily a parasite, however, as many saprophytes (moulds, &c.) germinate and develop a loose mycelium on living leaves, but only enter and destroy the tissues after the leaf has fallen; in some cases, however, these saprophytic epiphytes can do harm by intercepting light and air from the leaf (Fumago, &c.), and such cases make it difficult to draw the line between saprophytism and parasitism.
Ericaceae, Pyrolaceae, Gentianaceae, Orchidaceae, ferns, &c. Recent experiments have shown that the difficulties of getting orchid seeds to germinate are due to the absence of the necessary fungus, which must be in readiness to infect the young seedling immediately it emerges from the seed.
There is no warrant for the popular notion that genuine "mummy wheat" will germinate; on the other hand some seeds lose vitality in little more than a year.
Zoospores are of two kinds: (I) Those which come to rest and germinate to form a new plant; these are asexual and are zoospores proper.
(2) Those which are unable to germinate of themselves, but fuse with another cell, the product giving rise to a new individual; these are sexual and are zoogametes (Gr.
This is in consonance with the facts already mentioned that zoospores germinate forthwith, and that the sexually-produced cell or zygote enters upon a period of rest.
It is known that zoogametes, which usually conjugate, may, when conjugation fails, germinate directly (Sphaerella).
In rare cases the oosphere has been known to germinate without fertilization (Oedogonium, Cylindrocapsa).
Aplanospores would seem to represent zoospores arrested in their development; without reaching the stage of motility, they germinate within the sporangium.
Both aplanospores and akinetes may germinate with or without the formation of zoospores at the initial stage.
Gametes which fail to conjugate sometimes assume the appearance of zygospores and germinate in due course.
Fertilization has been observed at Naples; but it apparently depends on climatic conditions, as at Plymouth the oospheres have been observed to germinate parthenogenetically.
In these cases, however, the potential gametes may, failing conjugation, germinate directly, like the zoospores derived from unilocular sporangia.
Tetraspores are at first naked, but soon acquire a cell-wall and germinate without a period of rest.
They soon acquire a cell-wall, and germinate without a period of rest.
Another parable compared the kingdom of God to seed which, when once planted, must inevitably germinate; the process was secret and slow, but the harvest was certain.
They germinate only in the second year after sowing; in the course of their first year the seedlings attain a height of 6 to 12 in.
These zoospores escape and swim about in any film of moisture, and on going to rest take a spherical form, germinate and produce threads of mycelium as at K.
The sporangia may also germinate directly without undergoing division.
It is therefore obvious that, if the tubers are exposed to the air where they are liable to become slightly cracked by the sun, wind, hail and rain, and injured by small animals and insects, the spores from the leaves will drop on to the tubers, quickly germinate upon the slightly injured places, and cause the potatoes to become diseased.
In 1876, however, Cohn had seen the spores germinate, and Koch, Brefeld, Pratzmowski, van Tieghem, de Bary and others confirmed the discovery in various species.