. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. FERTILIZATION IN GYMNOSPERMS. 439 finds there a certain amount of moisture by means of wliich a tube is formed from one of the large cells. This extends directly Into the tissue of the nucellus, coming sooner or later into con- tact with the summit of the embryonal sac, and then affecting the corpusculesbelow. From the fertilized corpuscule tlie embrjo is developed.^ ' For the purpose of affording some means of comparison of the methods of reproduction in iiow
. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. FERTILIZATION IN GYMNOSPERMS. 439 finds there a certain amount of moisture by means of wliich a tube is formed from one of the large cells. This extends directly Into the tissue of the nucellus, coming sooner or later into con- tact with the summit of the embryonal sac, and then affecting the corpusculesbelow. From the fertilized corpuscule tlie embrjo is developed.^ ' For the purpose of affording some means of comparison of the methods of reproduction in iiowering plants and in tliose of a lower grade, the following brief notes concerning the reproduction in several of the groups of Cryptogams have been inserted: â (1) No sexual reproduction has yet been demonstrated in the very lowest forms of vegetntion. Such plants are tenned Protophytes. The fungi which are associated with fermentation and putrefaction, and certain of the simplest algae, are examples of the group. In the study of the Protophytes the beginner can examine with profit the cells of common yeast. Care should be taken to distinguish between the cells of the plant and the grains of starch with which compressed yeast is generally associated. The simplt; one-celled plants with chlorophyll which belong to this group can be found in almost any stagnant water. They are spherical, and aie fre- quently grouped in twos or fours. (2) The sexual process in Zygophytes is characterized by the confluence of the protoplasmic masses of two very similar cells by which a new mass is formed as the starting-point of the new indi- vidual. In most of these, zygojihytes there is no plain distinction of sex. Some of the lower moulds and many of the filamentous algae are examples of the group. Excellent specimens for study may be found in stagnant or slow-running water in spring and through the suni- mei'. By careful search it is possible to detect cases in which the process of conjugatio
Size: 1259px × 1985px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantanatomy, bookyea
