Notwithstanding the great progress made in hematology in recent years, the etiology of leukemia still remains in doubt. A review of the rapidly accumulating literature on the subject affords but little more than the clinical observations to substantiate any claim which has been assumed to be the cause of this important disease. Stengel1 has well stated that one who has seen a number of cases of acute leukemia will not wonder at the persistence with which investigators and clinicians hunt for a microbic origin. If we accept Löwett's theory of "protoplasm-like forms" as the etiologic factor of the disease, then we succeed in bridging the chasm which now exists between blood findings and clinical observations, but, unfortunately his investigations are as yet sub judice.
The morbid phenomena of acute infectious disease, e. g., chill, rapid rise and fluctuation of temperature, accelerated pulse, cardiac irregularity, vomiting, diarrhea, diminished urinary secretion,