Chapter II: COMPOUND PROTEIDS.--A. Compounds of a proteid (globulin) with an

iron-containing pigment, soluble in water and coagulable by heat and alcohol._ Hæmoglobin, oxyhæmoglobin, methæmoglobin, etc.

_B._ _Compounds of proteids with members of the carbohydrate group. Insoluble in water; soluble in very weak alkalies._--_a._ True mucins. _b._ Mucoids or mucinoids.

_C._ _Compounds of proteids with nucleic acid. Phosphorized bodies yielding by decomposition metaphosphoric acid. Insoluble in water and in pepsin-hydrochloric acid, but more or less soluble in alkalies._--Nucleins.

_D._ _Compounds of proteids with nucleins. Very soluble in dilute alkalies._--Nucleoalbumins, as casein of milk, and nucleoalbumins of cell-protoplasm and cell-nuclei, etc.