Arcuate: arched, bow-shaped, sharply crescent-shaped; strongly curved as in 



a drawn bow. 

 Areolate: with openings; with thin areas (areolae), usually circular, in the wall. 

 Articulate, Articulated: jointed; with segments. 



Asexual: referring to reproduction in which spores rather than gametes are used. 

 Asexual auxospore : a resting stage formed without union of gametes ( diatoms ) . 

 Attenuated: narrowed or tapering toward the ends. 

 Autocolony: colony of cells formed by tlie division of one or more cells of a 



mother colony; or by internal division of a cell to form a miniature colony 



( see Fediastrum, Oocystis, Volvox ) . 

 Autospore: a small replica of the parent cell formed internally, one or several 



togetlier. 

 Autotrophic: self- feeding; able to manufacture food. 



Auxospore: a resting spore formed by some diatoms, either sexual or asexual. 

 Axial chloroplasts: chloroplasts in tlie median plane of a cell, arranged along 



a median line. 

 Axis: the central or median plane of a figure, cell, or plant. 



Azygote, Azygospore: a spore similar in shape and wall markings to a zygo- 

 spore ( q.v. ) but formed without the union of sex cells. 

 Bacillar: rod-shaped. 

 Basidia-like : club-shaped. 



Basipetalous: developing from apex toward the base. 

 Benthon: organisms attached on the bottom of an aquatic habitat; deep-water 



life. 

 Biconic: in the shape of two cones with their bases together. 

 Bifurcate: divided into two portions, or branches, as in the forking of spines 



or lobes. 

 Bilateral: on two sides; arising on two sides; the same on two sides. 

 Biseriate: in two rows; with two series of cells. 

 Blepharoplast: small body (the central body) associated with the nucleus; in 



some flagellates, the body from which the flagellum arises. 

 Bulbous: bulb-like, swollen at one end. 



Caespitose (or Cespitose): clustered; in fascicles; forming a mat or tangle. 

 Calose: a substance appearing in the walls of the Siphonales which replaces 



cellulose. 

 Calyptra: a thickening; a thick covering or membrane at the tip of a trichome 



or organ (e.g. in Oscillatoria spp., Phormidium spp. ). 

 Canal: tube; fine channel, as in the wall of diatoms. 

 Capitate: with a head; swollen at one end, or at both ends. 

 Capitellate: slightly swollen or enlarged at one end. 



Carotene, Carotin: an orange-colored pigment, usually associated with chloro- 

 phyll. 

 Carpogone, Carpogonium: female sex organ in the Rhodophyceae. 

 Carpospore: spore arising from the fertilized egg in some Rhodophyceae. 

 Cartilaginous: tough but pliable. 

 Catenate: joined to form a chain. 

 Caudus: a tail-piece. 

 Central body: the central region of the blue-green algal cell, which upon 



staining shows the presence of chromatin granules; a granule associated 



with the nucleus in flagellated organisms. 

 Central nodule : the thickening on the inner face of the wall of some diatoms. 

 Centricae: diatoms which are radially symmetrical. 

 Centrifugal: developing from the center outward, or from a point outward. 



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