In the yolk are seen yolk-spherules in a protoplasmic network.
That no yolk spherules are present in the cells of the follicular epithelium, in which they could not fail to be detected, owing to the deep colour they assume on being treated with osmic acid.
Observations on the yolk spherules may be made either in living ova, in ova hardened in osmic acid, or in ova hardened in picric or chromic acids.
Schultz describes in the youngest ova of Torpedo the minute yolk spherules arranged in a semilunar form around the eccentric germinal vesicle.
It deserves to be especially noted, that when the yolk spherules are first formed, the peripheral layer of the ovum is entirely free from them, a feature which is however apt to be lost in ova hardened in picric acid (Pl.
They would probably be regarded by His as spherules of fatty material, unrelated to the true food yolk.
The two latter reagents, as well as alcohol, are however unfavourable for the purpose of this study, since by their action the yolk spherules appear frequently to be broken up and otherwise altered.
Footnote 393: The peculiar oval, or at times slightly rectangular and striated yolk spherules of Elasmobranchii are mentioned by Leydig and Gegenbaur (Pl.
The transverse markings in the yolk-spherules have been made oblique by the artist.
Two points about the spherules appear clearly to point to their being developed in the protoplasm of the ovum, and not in the follicular epithelium.
In the late stages, when the yolk spherules are fully developed, it is difficult to observe this network, but, as has been shewn in my monograph above quoted, it is still present after the commencement of embryonic development.
In hardened specimens the yolk-spherules become polygonal, and in ova treated with hot water prior to preservation are not unfrequently broken up.
The developing yolk spherules are not uniformly distributed but are collected in peculiar little masses or aggregations (Pl.
The yolk spherules commence to be formed in ova, of not more than 0.
The yolk spherules I find to be first developed in a peripheral layer of the vitellus.
The endoplasm, or the intracapsular sarcode, is rather opaque, finely granulated, and usually filled up by numerous small clearspherules of equal size, which are more or less regularly arranged and equidistant.
The part of the mesenteron with yolk-spherules forms the liver.
It is on the contrary to be regarded merely as a part of the ovum in which the yolk-spherules have attained to a very great bulk as compared with the protoplasm; sometimes even to the complete exclusion of the protoplasm.
The view that the yolk-spherules are of the same nature as the yolk cells is mainly supported by the case of Prostomum caledonicum, where the vitellarium produces the yolk particles which fill the ovum.
In its central part yolk-spherules become deposited, while the part adjoining the blastopore (anus) becomes elongated to give rise to the intestine.
In Reptilia the yolk-spherules are vesicles, somewhat similar to the white yolk-spheres of Aves, but as a rule without the highly refracting spheres in their interior.
Beneden yolk-spherules are formed in the protoplasm of the ovum itself, in addition to and independently of the surrounding yolk cells.
These yolk-spherules lie embedded in the protoplasm of the ovum, but are in most instances not distributed uniformly, being less closely packed and smaller at one pole of the ovum than elsewhere.
Thus the segments produced from that part of an egg where the yolk-spherules are most bulky, and where therefore the protoplasm is least concentrated, are larger than the remaining segments, and their formation proceeds more slowly.
The protoplasm of the ova, which is clear in the terminal division of the ovary, becomes in most forms filled lower down with yolk-spherules secreted in the body of the ova.
The eggs are developed in these sacks in a perfectly normal manner, and in many cases become filled with yolk-spherules which arise as differentiations of the protoplasm of the ovum.
There is thus a complete series of gradations between the investment of the ovum by a number of distinct cells, and its investment by a layer of fluid containing yolk-spherules in suspension.
The patent shot towers originally constructed in England obviate this evil by exposing the fused spherules after they pass through the cullender, to a large body of air during their descent into the water tub placed on the ground.
Yolk spherules are present in this disc as elsewhere, but are much smaller and of a different character.
The greater part of it is formed of peculiar oval spherules of food-yolk, held together by a protoplasmic network.
It contains numerous minute spherules of the same nature as the smallest white yolk spherules.
That the vesicles of steam examined in the sunshine were hollow it would seem there can be no doubt; and if so, there can be as little that Halley and the others were right in thinking the spherules of clouds to be hollow.
Epiblast cells from an unincubated blastoderm, treated with silver nitrate, shewing the regular hexagonal shape of the cells and the small spherules they contain.
These are exactly the motions that make the blue light of the sky which is due to spherules in the luminiferous ether, but little modified by the air.
Undoubtedly this is true; at least just before the final act of condensation takes place; and when the little hollow spherules collapse they are gathered together in drops of water larger or smaller according to the rapidity of condensation.
Gradually, however, the yellow sphere broke itself up into smaller spherules (Pl.
Gradually the nucleus divides, and the protoplasm also separates into two spherules (Pl.
The separate spherules now begin to lose their smooth outline, to throw out processes, and to show amoeboid movements like those of the creatures just described.
In many cases thesespherules of water, which compose clouds, are kept from uniting by a surplus of electric fluid; and fall in violent showers as soon as that is withdrawn from them, as in thunder storms.
On the bottom of a glass-retort suspended over a lamp, the like spherules collect, from which it is supposed that water never touches the bottom of any containing vessel; it must touch that which it wets.
The like spherules collect on an egg while boiling, which cannot be anything issued from the fire to the surface of the water, then precipitated on the egg.
They burned a puff ball of lycoperdon to charcoal spherules of about one-sixth the specific gravity of water.
Ooelitic limestone (oeon, an egg; lithos, a stone) is so named from the likeness of the tiny spherules which compose it to the roe of fish.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "spherules" in a variety of sentences. We hope that you will now be able to make sentences using this word.
