. Elementary botany. Botany. I50 MORPHOLOGY, forms two spcrmatozoids {sometimes only one) which arc of the same form as the zcKjgonidia but smaller, and yellnwish insteatl of screen. In some species a motile body intermedi- ate in size and color be- tween the spcrmatozoids and zooj^^onidia is first formed, which after swimming- around comes to rest on the oogonium, or near it, and develops what is called a " dwarf male pl?nt " from which the reai spermatozoid is '/ produced, p ^- ^T*,!"''', f ^ 3,18. oog-onia. - The i^nrtiriD or tnreafi or rjedo- . gonium showing upper half Oogo
. Elementary botany. Botany. I50 MORPHOLOGY, forms two spcrmatozoids {sometimes only one) which arc of the same form as the zcKjgonidia but smaller, and yellnwish insteatl of screen. In some species a motile body intermedi- ate in size and color be- tween the spcrmatozoids and zooj^^onidia is first formed, which after swimming- around comes to rest on the oogonium, or near it, and develops what is called a " dwarf male pl?nt " from which the reai spermatozoid is '/ produced, p ^- ^T*,!"''', f ^ 3,18. oog-onia. - The i^nrtiriD or tnreafi or rjedo- . gonium showing upper half Oogonia are formed di- Fig. 147. Portion of thread o f oedogonium showing antheridia. of egg open, and a sperina- recti\' fr(.)m one of the toxoid ready to enter. (After Klebahn). vegetative cells. In most species this cell first enlarges in diameter, so that it is easily detected. The protoplasm inside is the egg cell. The oogonium wail opens, a bit of the protoplasm is emitted, and the tpcrmatozoid then enters and fertilizes it (fig 148). Now a hard brown wall is formed around it, and, just as in spirogyra Fig. 149- Fig. 150. Fig. 151. Male nucleus just entering Male nucleus fusing with The two nuclei fused, and egg at left side. female nucleus. fertilization conijilete. Figs. 149-151.—Fertilization in cedogonium. (After Klebahn). .'ind vaucheria, it passes through a resting period. Atthe time of germinatiot it does not produce the thread-like plant again directly, but first forms fan zoospores exactly like the zoogunidia {fig. 152). These zoospores ther germinate and form the plant. 319. (Edogonium compared with spirogyra.—Now if we compare cedo- gonium with S[iirogvra, as we did in llie - g\ra. * iiowtli and di\isi(in o| iIk' lliread is limiled to eeruiin poiiions. Ihe sexiKil organs aie dilTerenliaKd. Tliev usually <lilTer in form and si/e from tlie vegetative cells, though liie uniuni is simjdy a changed vegetative. Please note that these images are extracted from scan
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