Abstract: A process and apparatus for forming fibers from attenuable materials, such as molten glass, by attenuating streams of glass from the bottom of a bushing wherein the bottom has downwardly presented wall portions at upper and lower levels. According to the disclosure the upper or lower wall portions are formed into series of bosses containing alveoles, each having a multiplicity of orifices in the lower wall portions. Filamentary material is manufactured by drawing at least one filament from each alveole independently of each other alveole regardless of whether or not the material has flooded the bottom surface of any boss. Controlled cooling permits the selective drawing of one or a plurality of filaments from each alveole.