Elementary botany (1898) (21223742761)

Title: Elementary botany

Identifier: elementarybotany00atki (find matches)

Year: 1898 (1890s)

Authors: Atkinson, George Francis, 1854-1918

Subjects: Botany

Publisher: New York, H. Holt and company

Contributing Library: The Library of Congress

Digitizing Sponsor: The Library of Congress

Text Appearing Before Image:

PROTOPLASM. 9 node. These internodes are peculiar. They consist of but a single "cell," and are cylindrical, with closed ends. They are sometimes 5-10 cm. long. 19. Internode of nitella.—For the study of an internode of nitella, a small one, near the end, or the ends of one of the " leaves " is best suited, since it is more transparent. A small portion of the plant should be placed on the glass slip in water with the cover glass over a tuft of the branches near the growing end. Examined with the microscope the green chlorophyll bodies, which form oval or oblong discs, are seen to be very numer- ous. They lie quite closely side by side and form in perfect rows along the inner surface of the wall. One peculiar feature of the arrangement of the chlorophyll bodies is that there are two lines, extending from one end of the internode to the other on opposite sides, where the chlorophyll bodies are wanting. These are known as neutral lines. They run parallel with the axis of the internode, or in a more or less spiral manner as shown in fig. 9. 20. Cyclosis in nitella.—The chlorophyll bodies are stationary on the inner surface of the wall, but if the microscope be properly focussed just beneath this layer we notice a rotary motion of particles in the protoplasm. There are small granules and quite large masses of granular matter which glide slowly along in one direction on a given side of the neutral line. If now we examine the protoplasm on the other side of the neutral line, we see that the movement is in the opposite direction. If we examine this move- lg', ' . ,, rr Portion of plant nitella. ment at the end of an internode the particles are seen to glide around the end from one side of the neutral line to the other. So that when conditions are favorable, such as temperature, healthy state of the plant, etc., this gliding of the particles or apparent streaming of the proto- plasm down one side of the " cell," and back upon the other, continues in an uninterrupted rotation, or cyclosis. There are many nuclei in an internode of nitella, and they move also. 21. Test for protoplasm.—If we treat the plant with a solution of iodine we get the same reaction as in the case of spirogyra and mucor. The proto- plasm becomes yellowish brown. 22. Protoplasm in one of the higher plants.—We now wish to examine, and test for, protoplasm in one of the higher plants.

Text Appearing After Image:

'

elementary botany book illustrations images from internet archive library of congress

1898

Library of Congress

http://commons.wikimedia.org/

public domain