The concurrence of bacteriuria and urinary calculi has long been known, and the opinion that some varieties of calculi, particularly the phosphatic, might result from microbic agencies has also been held. It is only going a step further, as Wright said in his introductory address on Vaccine Therapy, before the Royal Society of Medicine,1May 23, 1910, to search for a bacterial cause in connection with every case of urinary calculus. On the occasion of this particular lecture Wright reported on four cases, observed in the course of the daily routine work in the department of therapeutic immunization at St. Mary's Hospital, in which bacteria were discovered in the urine, and in which nephrolithiasis also existed. Recognizing the authority of this distinguished bacteriotherapeutist, and since the cases correspond so closely to those that have fallen to my observation, I shall quote Wright's report2as follows: