. The Protozoa. Protozoa. THE MASTIGOPHORA 119 forms that there is apparently good reason for supposing them to play a similar physiological role. In the green flagellates there are often distinct concretions, regarded by some observers as lenses ; and if Pouchet ('86) is correct, a still more striking differentiation is found among the Dinoflagellidia. The so-called eye of Gymnodinium con- sists of a transparent, highly refracting lens, rounded at its free extremity, and always directed forward (Pouchet). The inner sur- face is embedded in a hemispherical, cap- like mass of red or black pigme
. The Protozoa. Protozoa. THE MASTIGOPHORA 119 forms that there is apparently good reason for supposing them to play a similar physiological role. In the green flagellates there are often distinct concretions, regarded by some observers as lenses ; and if Pouchet ('86) is correct, a still more striking differentiation is found among the Dinoflagellidia. The so-called eye of Gymnodinium con- sists of a transparent, highly refracting lens, rounded at its free extremity, and always directed forward (Pouchet). The inner sur- face is embedded in a hemispherical, cap- like mass of red or black pigment, which Pouchet considered a choroid. Thelenses develop by the union of from six to eight refringent corpus- cles, while the organ- ism is still encysted or while undergoing fission. The choroid likewise results from the union of several of the pigment gran- ules. Considerable doubt has, however, been thrown upori these observations by subsequent ob- Other inclusions of interest are the thread-like structures which are common among holotrichous ciliates, and which occur sporadically in other Protozoa. Among the Mastigophora they are found in only two cases {Gony- ostommn Klochmann and Polykrikos Butschli). In the former they are trichocysts similar to those of the ciliate Paramceciiim and allied forms, but in the latter they are true nematocysts, comparable to those of the Fig. 65. — Sjiiiura uvella Ehr. Each individual of the colony is surrounded by a gelatinous- membrane, and possesses two chromatophores (c) and a nucleus B. The FlAgella The most characteristic part of a flagellate is its motile organ, the flagellum. This consists of a vibratile filament usually tapering to a fine point, although in some cases { in all Choanoflagellida) it is 1 Cf. Penard ('88).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not p
Size: 1565px × 1597px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcalkinsg, bookcentury1900, bookdecade1900, bookyear1901
