A REVIEW OF RECENT WORK ON THE MECHANISM OF URINE FORMATION.

PREFACE.  The study of the mechanism of urine formation is still one of the most fascinating fields of physiologic research, as is witnessed by the output of papers. Aside from its direct practical application, the kidney owes its chief interest to the fact that, of all the glands, its functions seem best adapted to a simple physicochemical explanation; which, being once found, might furnish a key to the more complicated so-called vital phenomena. On the other hand, its anatomic structure is peculiarly complex and makes a complete isolation of its functions a problem which continues to elude the utmost ingenuity of skilful investigators.Recourse must be had, therefore, to indirect methods, to deductions and theories, which in turn rest on assumptions more or less definitely proved, or more or less probable. Such methods are peculiarly exposed to the danger of "reasoning around a circle." The temptation is ever present to