The characters are described of a hitherto unrecorded species of Haemophilus that has
been isolated, usually as the L-form, from many chronic pure and mixed infections in infants,
especially after antibiotic therapy. It most closely resembles H. aphrophilus among recorded
species, but is physiologically and serologically distinct from a type culture of this organism
and differs from it in the sugar composition of the cell wall. Some strains have antigens in
common with H. influenzae, but all differ widely from this species in physiological characters.