Differential counts were made in 194 cases, including influenza, influenzal pneumonia and influenzal complications. We have taken the average percentage of each type of cell for the groups, which are purely numerical divisions based on the leucocytic count. No differentiation is made for the various clinical divisions of the epidemic in the following table: LEUCOCYTES 2,000–8,000. P. E. L.M. S.M. Trans. Total counts 86 66% 1% 13% 17% 3% LEUCOCYTES 8,000–10,000. P. E. L.M. S.M. Trans. Total counts 33 69% 1% 11% 16% 3% LEUCOCYTES 10,000–20,000. P. E. L.M. S.M. Trans. Total counts 45 76% 2% 10% 19% 3% LEUCOCYTES 20,000–30,000. P. E. L.M. S.M. Trans. Total counts 17 79% 2% 8% 7% 4% LEUCOCYTES 30,000–40,000. P. E. L.M. S.M. Trans. Total counts 13 85% 1% 5% 6% 3% The differential count in general indicates an increase in the polymorphonuclear leucocytes as the total leucocytic number increases. This is really what one would expect. There also seems to be an increase of the large mononuclear cells, with a slight diminution in the small mononuclear elements, particularly in the count below 10,000. Abnormal cells were encountered very seldom. One can hardly say that the epidemic has a characteristic differential blood picture, except, perhaps, that an increase of the large mononuclears is present in the low counts. This, however, may hold true for any leucopenia. _Conclusions_ 1. Epidemic influenza is often accompanied by a transient slight albuminuria with a few red blood cells and casts. Acute nephritis as a clinical entity does not appear to be other than a rare sequel. 2. Epidemic influenza tends to produce a leucopenia. 3. A leucocytosis in influenza, as a rule, indicates a secondary infection. 4. The pneumonia following influenza shows, as a rule, but a very moderate leucocytosis, while, on the other hand, the presence of a leucopenia is by no means infrequent. We are greatly indebted to Miss R. Thompson, Messrs. Mock, Frost, Marshall and Scott for their assistance in this work at the Magee Hospital. THE TREATMENT OF INFLUENZA By W. W. G. MACLACHLAN, M. D.