Elementary botany . Fig. and open archegonium of fern (Adiantum cuneatum) with spermatozoids makingtheir way down through the slime to the egg. tissue of the prothallium. The egg is in the larger part. Thespermatozoids when they are swimmingaround over the under surface of the pro-thallium come near the neck, and here theyare caught in the viscid substance whichhas oozed out of the canal of the arche-gonium. From here they slowly swimdown the canal, and finally one sinks intothe egg, fuses with the nucleus of the latter,and the egg is then fertilized. It is nowready to grow and deve
Elementary botany . Fig. and open archegonium of fern (Adiantum cuneatum) with spermatozoids makingtheir way down through the slime to the egg. tissue of the prothallium. The egg is in the larger part. Thespermatozoids when they are swimmingaround over the under surface of the pro-thallium come near the neck, and here theyare caught in the viscid substance whichhas oozed out of the canal of the arche-gonium. From here they slowly swimdown the canal, and finally one sinks intothe egg, fuses with the nucleus of the latter,and the egg is then fertilized. It is nowready to grow and develop into the fernplant. This brings us back to the sporo- phyte, which begins with the fertilized Fertilization in a fern Marattia). s/>, spermato-zoid fusing with the nu-cleus of the egg. (After Campbell. 1 Sporophyte. 558. Embryo.—The egg first divides into two cells as shown in fig. 228, theninto four. Now from each one of these quandrants of the embryo a definitepart of the plant develops, from one the first leaf, from one the stem, fromone the root, and from the other the organ which is called the foot, and which FERNS. 269 attaches the embryo to the prothallium, and transports nourishment for theembryo until it can become attached to the soil and lead an independent ex-istence. During this time the wall of the archegonium grows somewhat toaccommodate the increase in size of the embryo, as shown in figs. 312, soon the wall of the archegonium is ruptured and the embryo emerges,the root attaches itself to the soil, and soon the prothallium dies. The embryo is first on the under side of the prothallium, and the first leaf
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
