n pl :  minute granules in protoplasm once regarded as its ultimate formative units but now physically equated with mitochondria
 
Altmann, Richard (1852-1900), German histologist. Around 1890 Altmann advanced his theory that the fundamental units of protoplasm are granular particles whose existence he inferred from particles observed at the limits of resolution of the light microscope. They subsequently became identified with his name. The particles now are thought to be cellular organelles known as mitochondria whose morphology and cellular function have been worked out with the aid of the much greater resolving power of the electron microscope.
 
   
 
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