Mi cro nu' cle us, see Nucleolus.
Mimicry, a method of protection due to the resemblance of an unprotected to a well-protected animal.
Mol lus' ca, the branch of animals to which clams, snails, etc., belong.
Mo nœ' cious, reproductive organs in different regions of the same individual.
Mouth, the anterior opening into the digestive cavity.
Neph rid' i um (pl. neph rid' i a), a tubule functioning as a kidney in some of the worms.
Net' tle cells, the stinging cells found in the cœlenterates.
Noc tur' nal, pertaining to night.
Nu cle' o lus (pl. nucleoli), a very small, dense, dark-staining body, either within the nucleus or near it. In the latter case it is often called the paranucleus or micronucleus.
Nu' cle us (pl. nuclei), a dense bit of protoplasm usually near the center of a cell, often staining dark.