. Synopsis of the naviculoid diatoms. Presented to the R. Swedish Academy of Sciences May 10, 1893. Diatoms. A. complexa, 500 times magnified. A. incerta, 500 times magnified. Of A. incerta I have had an opportunity of examining numerons living specimens. This species has also a single chromatophore-plate along the ventral side of the zone, enclosed in a plasma-mass which sends fine plasma-threads to the walls of the frustule. If the living frustules be suddenly killed by a boiling con- centrated solution of mercuric chloride in alcohol, and then by washing freed from mercuric salt, they may b
. Synopsis of the naviculoid diatoms. Presented to the R. Swedish Academy of Sciences May 10, 1893. Diatoms. A. complexa, 500 times magnified. A. incerta, 500 times magnified. Of A. incerta I have had an opportunity of examining numerons living specimens. This species has also a single chromatophore-plate along the ventral side of the zone, enclosed in a plasma-mass which sends fine plasma-threads to the walls of the frustule. If the living frustules be suddenly killed by a boiling con- centrated solution of mercuric chloride in alcohol, and then by washing freed from mercuric salt, they may be stained with different dyes. Carmine colours the nucleus, which is placed above the plate and on its centre. Stained with chrysoidine numerous granules in the plasma-mass take an intensely yellow colour, and are probably elseoplasts, as fatty matters are intensely coloured by the dye. Auricula minuta has also a single chromotophore-plate along the ventral side, and at the primordial stratum of the plasma a number of small granules, possibly geline-secreting organs. Auxospores. In A. minuta a single globular auxospore is formed out' of two frustules. In the annexed sketches a and c represent a frustule in living state, b a frustule in the state of division. Fig. d shews two frustules enclosed in a mucous mass, the first stage of the conjugation. In e the auxospore is formed and ienclosed between the empty valves; f seems to represent an mature auxospore, and g two frustules, to judge from the size, probably formed out of the auxospore. Some extreme forms of Auricula have a very peculiar appearance, but by intermediate steps they are connected on one hand with Amphiprora, on the other with Amphora, so nearly indeed that no line of demarcation may be traced between Am- phora and Auricula. All species of Auricula are marine and pelagic. Some forms are thin and membranaceous. Others have strong valves, but thin connecting zones, so that entire frustules are rarely to be found in g
Size: 1199px × 2083px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectdiatoms, bookyear1894
