Emery's book is an excellent presentation of the main facts, principles and theories concerned in these subjects of immunity and specific therapy. From the literary point of view it is unusually good, considering that the subjects are difficult to present interestingly. Its interest and instructive value are further increased by the many apt illustrations and analogies which the author has at his command.
The first chapter, "Introductory and General," defines immunity and considers the various types, as natural and acquired, active and passive, mixed immunity and local immunity; discusses the character of the virulence of microorganisms and the means of increasing it or lowering it for purposes of vaccination; and, finally, devotes two pages to the theories of immunity. Emery's definition of immunity seems very wide in at least this regard: that he sometimes refers to the non-occurrence of a disease (as gout) as indicating immunity on the part of