In some genera the forms are simple, while in others the frustules are connected together in ribbon-like filaments, or form, as in other cases, zigzag chains.
One of the first phenomena which comes under the notice of the observer is the extraordinary power of motion with which the frustules are endowed.
Some species move slowly backwards and forwards in pretty much the same line, but in the case of Bacillaria paradoxa the motion is very rapid, the frustules darting through the water in a zigzag course.
All manner of beautiful sculpturing marks these beautiful frustules as they are called; in some cases they are perforated and the living matter from within passes through the pores and forms a jelly-like covering for the little plant.
The living matter of which the plant is composed pushes the frustules apart and divides across the middle.
Nitzsch, of Halle) Frustules usually free, sometimes enclosed in tubes or united into a filament.
In all species of Diatoma a punctum, or pore, is observed, usually at alternate ends of the two valves, by means of which a communication exists between adjoining frustules and causes them to adhere in zig-zag chains when partially separated.
The frustules are usually bent along the longitudinal axis, probably because of the attachment to the curved stems of water-plants.
Lithodesmium is characterized by the envelopment of the frustules by a cellular membrane which does not appear, evidently, in Ditylum.
The valves are covered with fine dots, and near each end of the frustules is a projecting rim encircling it, and appearing as a curved line extending beyond the margin of the frustule in the front view.
To illustrate the forms and markings of the frustules and valves, we may select the following species taking first those which occur in fresh water.
The form of thefrustules is very different in the various genera and species, as represented in Pl.
The suture is the line at which the division of the frustules takes place in the formation of new individuals.
It will also be noticed that many of the free frustules move slowly across the field of the microscope; but the cause of the motion is unknown.
When the frustules are examined in the living state, the cell-contents resemble those of ordinary vegetable cells, excepting in regard to the colour, and exhibit granules and globules, and sometimes a nucleus is visible.
The frustules form short filaments, attached by a little gelatinous cushion.
At the same time a siliceous band, encircling the frustulesat the line of suture, is formed to fill up the interval between the edges of the parent valves; this is the hoop (Pl.
In some species, the frustules are attached to foreign bodies by means of a gelatinous cushion (Pl.
These threads are the cases of a minute microscopic body, called Gaillonella ferruginea (Figure 15), associated with the siliceous frustules of other fresh-water algae.
This stone, when examined with a powerful microscope, is found to consist of the siliceous plates or frustules of the above-figured Diatomaceae, united together without any visible cement.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "frustules" in a variety of sentences. We hope that you will now be able to make sentences using this word.
