+Yellow Fever.+ Sternberg and Havelburg have both isolated bacilli from cases of yellow fever; but the organism discovered by Sanarelli, the _Bacillus icteroides_, is now accepted as the causal agent of the disease. It is a small, short rod, with round ends, and generally united in pairs; it has various pleomorphic forms; it grows well on all the ordinary media; it is killed in sea-water at 60° C., and also by direct sunlight in a few hours.
+Diarrhœa of Infants.+ From time to time different organisms have been isolated in this diseased condition. _Bacillus coli_ and _B. enteriditis sporogenes_ (Klein) have been held responsible for it. W. D. Booker, of Johns Hopkins University, sums up an extended research into the question as follows:
"No single micro-organism is found to be the specific exciter of the summer diarrhœa of infants, but the affection is generally to be attributed to the result of the activity of a number of varieties of bacteria, some of which belong to well-known species, and are of ordinary occurrence and wide distribution, the most important being the streptococcus and _Proteus vulgaris_.
"The first step in the pathological process is probably an injury to the epithelium from abnormal or excessive fermentation, from toxic products of bacteria, or from other factors.
"Bacteria exert a direct injury upon the tissues in some instances, whereas in others the damage is brought about indirectly through the production of soluble poisons."
+Actinomycosis.+ This disease affects both animals and man. As Professor Crookshank points out, it has long been known in this country,[100] but its various manifestations have been mistaken for other diseases or have received popular names.
Here we can only mention the most outstanding facts concerning the disease. It is caused by the "ray fungus," or _Streptothrix actinomyces_, which, growing on certain cereals, often gains entrance to the tissues of man and beast by lacerations of the mucous membrane of the mouth, by wounds, or by decayed teeth. Barley has been the cereal in question in some cases. The result of the introduction of the parasite is what is termed an "infective granuloma." This is, generally speaking, of the nature of an inflammatory tumour composed of round cells, epithelioid cells, giant cells, and fibrous tissue, forming nodules of varying sizes. In some cases they develop to large tumours, in others they soon break down. Actinomycosis in some ways closely resembles tuberculosis in its tissue characters.