from
The Collaborative International Dictionary of English v.0.48
Diatom \Di"a*tom\ (d[imac]`[.a]*t[o^]m), n. [Gr. dia`tomos cut
in two. See {Diatomous}.]
1. (Bot.) One of the {Diatomace[ae]}, a family of minute
unicellular Alg[ae] having a siliceous covering of great
delicacy, each individual multiplying by spontaneous
division. By some authors diatoms are called
{Bacillari[ae]}, but this word is not in general use.
[1913 Webster]
2. A particle or atom endowed with the vital principle.
[1913 Webster]
The individual is nothing. He is no more than the
diatom, the bit of protoplasm. --Mrs. E. Lynn
Linton.
[1913 Webster]