. Botany of the living plant. Botany; Plants. 4i6 BOTANY OF THE LIVING PLANT branches {progametangia), either of the same mycelium (Sporodinia), or of distinct myceiia [Mucor stolonifer, and other Mucors), growing towards one another, meet at their apices (Fig. 314). From the end of each a conjugating cell or gaynetangium containing protoplasm with many nuclei is cut off by a trans- verse septum from the basal sus- pensor. Their apices flatten, and the gametangia fuse, the wall separating them being absorbed. Many nuclei are involved ; these fuse in pairs and the result on maturation is a zygo
. Botany of the living plant. Botany; Plants. 4i6 BOTANY OF THE LIVING PLANT branches {progametangia), either of the same mycelium (Sporodinia), or of distinct myceiia [Mucor stolonifer, and other Mucors), growing towards one another, meet at their apices (Fig. 314). From the end of each a conjugating cell or gaynetangium containing protoplasm with many nuclei is cut off by a trans- verse septum from the basal sus- pensor. Their apices flatten, and the gametangia fuse, the wall separating them being absorbed. Many nuclei are involved ; these fuse in pairs and the result on maturation is a zygospore (Fig. 314, 4). The large protoplast is stored with nutritive material, while the outer wall thickens, often forming characteristic bosses externally (Fig. 314, 3, 4)- In this condition the zygospore may undergo a period of rest, and is resistant to unfavourable con- ditions. But suitable conditions induce germination, and they de- termine what follows. Sometimes there is a formation of a vegetative mycelium, sometimes, as in Fig. 314, 5, an immediate formation of Mucor Mucedo. Different stages in the forma- a sporangium I the Spores prO- tion and germination of the zygospore, i =two . , « i r progametangia in contact. 2 =septation of the duced in the latter are the tirSt two gametangia. 3 = more advanced stage ; the conjugating cells are still distinct from one stage of the new gametophyte. another. 4 =ripe zygospore (b) between the . suspensors (a). 5 =germinating zygospore with A remarkable fact IS the OCCUT- germ-tube bearing a sporangium. (After Brefeld.) ' (1-4x225; 5 x circa 60.) (From v. Tavei.) rence in some Mucors 01 Azygo- (From Strasburger.) , spores," that is, bodies that re- semble zygospores in their structure and covering, but are produced without any fusion. According to their power and readiness for conjugation the Mucorales have been divided into two groups. The Homothallic, which form zygospores on two branches of the same mycelium, so that by sow
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Keywords: ., bookcentury1900, bookpublis, booksubjectbotany, booksubjectplants
