. Foundations of botany. Botany; Botany. 280 FOUNDATIONS OF BOTANY Do both occur on the same thallus ? On what part of the thallus do they occur, and do they difEer in this respect ? 340. Antheridia. — The antheridia are formed as outgrowths from the upper surface of the crenate receptacle, but by further growth of the receptacle they become imbedded. They should be examined under a high power and sketched in outline. The anther- idium produces numerous motile antherozoids, each with two cilia. 341. Archegonia and Sporophytes. — The receptacle with recurved rays bears the archegonia. Note whet
. Foundations of botany. Botany; Botany. 280 FOUNDATIONS OF BOTANY Do both occur on the same thallus ? On what part of the thallus do they occur, and do they difEer in this respect ? 340. Antheridia. — The antheridia are formed as outgrowths from the upper surface of the crenate receptacle, but by further growth of the receptacle they become imbedded. They should be examined under a high power and sketched in outline. The anther- idium produces numerous motile antherozoids, each with two cilia. 341. Archegonia and Sporophytes. — The receptacle with recurved rays bears the archegonia. Note whether they occur above or below and in what relation to the rays. How are the archegonia protected ? Note the cells which surround the central canal and form the elongated neck of the archego- nium. Does the archegonium open Tipward or downward ? At the base look for the germ-cell. The antherozoids enter the central canal and penetrating to the egg-ceU fertilize it, after which it begins to divide and grows into a sporophyte. In the older specimens, therefore, the sporophjrtes will be found more or less developed. The archegonium remains upon the tip of the sporophytes. The mature sporophyte contains the spores and also peculiar elongated tapering threads with spiral thickenings. These are called Fia. 205.—Sectional View of Female Keceptacle of Marchantla. (x 5.) 342. Hepaticse. — Marehantia represents only a small division of the Hepaticce, and is not typical of tlie larger number of species. In spite of this it is chosen for study, because it is widely distributed and more available for study than mosl others. In most species the fruit lasts but a little whUe and good material is hard to obtain. In Marehantia the fruiting organs are abundant, more gradual in their development, and more persistent. Marehantia and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearanc
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