and probably also in bronchiectasis (Allison et al., 1943), is responsible for the formation of a very tenacious greenishyellow mucopus. Such pus in the nasopharynx may well produce a cough resembling a whoop. Summary From per-nasal swabs of 650 children aged 0-4 years 32 capsulated H. influenzae strains have been isolated. Type f was found 11 times, type e 8 times, and type b 6 times, the other three types occurring less often. The fact that the most frequently isolated types were not H. influenzae type b, while type b was the causative agent in all of 41 cases of H. influenzae meningitis occurring during the same period in Leeds and various other parts of England and Wales, suggests that this type is more virulent for man than the other five known H. influenzae typ2s. We are greatly indebted to Professor J. W. McLeod-for access to the bacteriological material. We are glad to acknowledge Dr. G. C. Turner's help in providing us with H. influenzae strains from the whooping-cough inquiry after one of us (B. D.) had left the department. REFRENCES

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