Eine Wanderung durch Oberkrain

Ohne Zusammenfassung     

Eine botanische Wanderung in der Mark Brandenburg

Ohne Zusammenfassung     

Die Wanderung der Pigmentgranula in der Epidermis beim physiologischen Farbwechsel von Carausius morosus

Carausius morosus is one of the few insects exhibiting physiological colour change in the epidermal cells. The distribution of ommochromes, carotinoids, and pterindines is analysed in light and dark adapted animals.In light adapted animals the ommochrome granules are concentrated at the proximal cell membrane. During dark adaption they move to the distal cell membrane, dispersing there over the whole cell forming a shield of dark pigment. The carotinoid granules behave in a similar way. The rod shaped pteridine granules are concentrated in the distal half of the epidermis. They show no daytime dependent movements. However, they take part in the physiological colour change indirectly. Apparently, biliverdin is not attached to granules but dissolved in the epidermal cells.     

Die Cnidogenese der Octocorallia (Anthozoa,Cnidaria): II. Reifung,Wanderung und Zerfall von Cnidoblast und Nesselkapsel

Migration of cnidoblasts has never been observed in Anthozoa. In contrast to hydrozoans, anthozoans are repeatedly reported to develop nematocysts locally without migration in the entoderm as well as in the ectoderm. The majority of the nematocysts studied in different Octocorallia species (Alcyonaria:Alcyonarium digitatum, Parerythropodium coralloides; Gorgonaria:Pseudopterogorgia aerosa; Pennatularia:Veretillum cynomorium) originate from the ectoderm of the scapus, where, however, no mature nematocysts occur. Cnidoblasts containing immature nematocysts accumulate in the distal scapus, from where they migrate singly like amoebae into the pinnulae of the tentacles. The nematocysts mature during migration, during which the capsular matrix becomes completely electron-translucent. Only in the oral disc, where few nematocysts occur, do they mature locally without migration. In the Octocorallia, nematocyst development and maturation takes places only in the ectoderm. Development of nematocysts has never been observed in the entoderm, nor in the pharynx; this demonstrates its entodermal origin. The entoderm contains only degenerated or phagocytized nematocysts. Contrary to hydrozoans, the mature anthozoan cnidocyte is rounded and has no processes to the mesogloea. Instead of a cnidocil it has a ciliary cone consisting of a normal flagellum, stereocilia and macrovilli. The cnidocyte is characterised by abundant electron-translucent cytoplasm and nematocyst-anchoring structures made up of cross-striated, collagen-like fibrillae and a fibrous basal ring. The position of the cross-striated fibrillae is distally similar to that of the supportive rods in hydrozoan cnidoblasts. The present study clearly demonstrates that structure and, possibly, function of an octocorallian cnidocyte is much simpler than that of a hydrozoan cnidocyte. On the other hand, cnidoblast migration, occurring in Hydrozoa as well in Octocorallia, turned out to be a much older phylogenetic character than was formerly believed.