HALOGEN n.
An electro-negative element or radical, which, by combination with a metal, forms a haloid salt; especially, chlorine, bromine, and iodine; sometimes, also, fluorine and cyanogen. See Chlorine family, under Chlorine.
PHYLOGENESIS; PHYLOGENY n.
The history of genealogical development; the race history of an animal or vegetable type; the historic exolution of the phylon or tribe, in distinction from ontogeny, or the development of the individual organism, and from biogenesis, or life development generally.
THALLOGEN n.
One of a large class or division of the vegetable kingdom, which includes those flowerless plants, such as fungi, algæ, and lichens, that consist of a thallus only, composed of cellular tissue, or of a congeries of cells, or even of separate cells, and never show a distinction into root, stem, and leaf.…