A cigarette comprising: a lighting end and a mouth end; a mouth end piece segment disposed at the mouth end; an aerosol-generation system disposed between the lighting end and the mouth end piece segment, the aerosol-generation system including (i) a heat generation segment immediately adjacent the lighting end, said heat generation segment having a length and including a heat source (40; 440; 740; 840; 940) and an insulation layer (42; 442; 748; 842; 942) of flame-retardant material, the insulation layer (42; 442; 748; 842; 942) comprising: about 20 to about 25 percent, by weight, wood pulp, and (ii) an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end; a piece of outer wrapping material oriented to provide an overwrap (i) around the aerosol-generating segment for at least a portion of its length, and (ii) around the heat generation segment for the length of that segment; those segments being connected together by the overwrap to provide a cigarette rod; and the mouth end piece segment being connected to the cigarette rod using tipping material, characterized in that the insulation layer (42; 442; 748; 842; 942) further comprises about 40 to about 50 percent, by weight, flue-cured tobacco lamina, and about 20 to about 25 percent, by weight, water-soluble flue-cured tobacco stems extract, wherein the insulation layer (42; 442; 748; 842; 942) comprises a treatment of ammonium chloride and is configured with an inner-facing geometry configured to complementarily engage and longitudinally retain the heat source (40; 440; 740; 840; 940) within the heat generation segment. a lighting end and a mouth end; a mouth end piece segment disposed at the mouth end; an aerosol-generation system disposed between the lighting end and the mouth end piece segment, the aerosol-generation system including (i) a heat generation segment immediately adjacent the lighting end, said heat generation segment having a length and including a heat source (40; 440; 740; 840; 940) and an insulation layer (42; 442; 748; 842; 942) of flame-retardant material, the insulation layer (42; 442; 748; 842; 942) comprising: about 20 to about 25 percent, by weight, wood pulp, and (ii) an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end; (i) a heat generation segment immediately adjacent the lighting end, said heat generation segment having a length and including a heat source (40; 440; 740; 840; 940) and an insulation layer (42; 442; 748; 842; 942) of flame-retardant material, the insulation layer (42; 442; 748; 842; 942) comprising: about 20 to about 25 percent, by weight, wood pulp, and (ii) an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end; a piece of outer wrapping material oriented to provide an overwrap (i) around the aerosol-generating segment for at least a portion of its length, and (ii) around the heat generation segment for the length of that segment; those segments being connected together by the overwrap to provide a cigarette rod; and the mouth end piece segment being connected to the cigarette rod using tipping material, characterized in that the insulation layer (42; 442; 748; 842; 942) further comprises about 40 to about 50 percent, by weight, flue-cured tobacco lamina, and about 20 to about 25 percent, by weight, water-soluble flue-cured tobacco stems extract, wherein the insulation layer (42; 442; 748; 842; 942) comprises a treatment of ammonium chloride and is configured with an inner-facing geometry configured to complementarily engage and longitudinally retain the heat source (40; 440; 740; 840; 940) within the heat generation segment. about 20 to about 25 percent, by weight, water-soluble flue-cured tobacco stems extract, wherein the insulation layer (42; 442; 748; 842; 942) comprises a treatment of ammonium chloride and is configured with an inner-facing geometry configured to complementarily engage and longitudinally retain the heat source (40; 440; 740; 840; 940) within the heat generation segment.