Elementary botany . Fig- 139. 302. Vaucheria sessi-lis; the sessile vauche- Young anthcridium and oogonium of Vaucheria ses- . T , . , silis, before separation from contents of thread by a Tia. In TillS plant me septum. t -i sexual organs are sessile,that is they are not borne on a stalk as in some other sexual organs usually occur several in a group. Fig. 139represents a portion of a fruiting plant. H4 MORPHOLOGY. 303. Sexual organs of vaucheria. Antheridium.—The antheridia are short, slender, curved branches from a mainthread. A septum is formed which separates an end portionfrom
Elementary botany . Fig- 139. 302. Vaucheria sessi-lis; the sessile vauche- Young anthcridium and oogonium of Vaucheria ses- . T , . , silis, before separation from contents of thread by a Tia. In TillS plant me septum. t -i sexual organs are sessile,that is they are not borne on a stalk as in some other sexual organs usually occur several in a group. Fig. 139represents a portion of a fruiting plant. H4 MORPHOLOGY. 303. Sexual organs of vaucheria. Antheridium.—The antheridia are short, slender, curved branches from a mainthread. A septum is formed which separates an end portionfrom the stalk. This end cell is the antheridium. Frequently itis collapsed or empty as shown in fig. 140. The protoplasm in. Fig. sessilis, one antheridium between two oogonia. the antheridium forms numerous small oval bodies each with twoslender lashes, the cilia. When these are formed the antherid-ium opens at the end and they escape. It is after the escapeof these spermatozoids that the antheridium is collapsed. Eachspermatozoid is a male gamete. 304. Oogonium.—The oogonia are short branches also, butthey become large and , % somewhat oval. The / * septum which separates theprotoplasm from that ofthe main thread is as wesee near the junction ofthe branch with the mainthread. The oogonium,as shown in the figure, isusually turned somewhatto one side. When mature the pointed end opens and a bit of theprotoplasm escapes. The remaining protoplasm forms the largerounded egg cell which fills the wall of the oogonium. In someof the oogonia which we examine this egg is surrounded by athick brown wall, with starchy and oily contents. This is the
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