Intricate: tangled. 



Investment : an inclosing membrane or envelope. 



Isochrysid: cells bearing two flagella of equal length in Chrysophyceae. 



Isodiametric: having diameters equal. 



Isogamous: sex cells similar to one another in size, shape, and behavior. 



Isokontae {Isokontean): plants which have vegetative or reproductive cells 



equipped with flagella (usually 2) of equal length. 

 Isthmus: narrow part of the desmid cell connecting two semicells (cell halves). 

 Karyokinesis: division of the nucleus; segregation of nuclear material in cell 



division. 

 Keel: a flange on the valve of some diatoms. 



Laciniate: torn; with a cut or lacy margin, or lace- work surface. 

 Lacuna ( Lacunate ) : an opening ( with spaces ) . 

 Lageniform: flask-shaped. 



Lamellate, Lamellated, Lamellose: layered, vdth layers. 

 Laminate: plate-like. 

 Lanceolate: lance-shaped; long and narrow with subparallel margins but 



tapered at the apex. 

 Lateral conjugation: sexual reproduction involving a joining to two contiguous 



cells in the same filament (e.g., in some species of Spirogyra). 

 Lenticular: lens-shaped; with two convex surfaces. 

 Leucosin: a white food reserve material found in most Heterokontae. 

 Limnoplankton: drifting organisms in lake water. 

 Littoral: in shallow water near shore; on the shore. 

 Longitudinal furrow: a groove in dinoflagellates lying parallel with the long 



axis, at right angles to the transverse furrow. 

 Loculiferous: with small chambers or compartments. 



Lorica: a shell or case built around but separate from the living protoplast. 

 Lumen: a cavity, especially the space left in a cell after spores or gametes have 



escaped. 

 Lubricous: slippery. 

 Lunate: crescent-shaped; moon-shaped. 



Macrogamete: the larger of two sizes of swimming gametes (e.g., Stichococcus). 

 Macrandrous: having male plants that are as large or nearly as large as the 



female plants ( Oedogoniaceae ) . 

 Macrozoospores: the larger of two sizes of zoospores (e.g., Ulothrix). 

 Mammillate: with nipple-like protuberances. 

 Marl: calcareous deposit formed by some algae, especially Chara. 

 Matrix: investing or surrounding matter, especially mucilaginous material sur- 

 rounding cells. 

 Median constriction: a pinched-in or narrowed region in central portion of cell 



or thallus. 

 Membranous, Membranaceous: like a membrane, a thin layer. 

 Meristematic: referring to cells with the ability to divide rapidly. 

 Mesospore: middle one of three layers in the wall of zygospores. 

 Metabolic: changeable in form, varying in shape from time to time (e.g., 



Euglena ) . 

 Microgamete: the smaller of two sizes of swimming gametes (e.g., Stichococ- 

 cus). 

 Microspores: minute, spore-like bodies formed by some diatoms, questionably 



sexual or asexual. 

 Microzoospores: smaller of two sizes of zoospores in Ulothrix; spores which 



swarm for 2 to 6 days without germination. 



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