St. Louis, June 20, 1906. To the Editor: —The caustic criticism of the practice of using nitroglycerin in the treatment of pneumonia, in the article on "The Treatment of Lobar Pneumonia," by E. Russell Zemp, inThe Journal, May 26, calls for some defense of a valuable but much abused and misused drug. Dr. Zemp states dogmatically that "nitroglycerin most certainly paralyzes the pneumogastric and the respiratory and vasomotor systems," also that "no one who clearly understands the physiologic action of this drug can be excused for killing a patient with pneumonia by its use." As a matter of fact, the physiologic action of nitroglycerin has not as yet been clearly established. The recent study of the drug by Dr. H. P. Loomis, "Limitations of the Value of Nitroglycerin as a Therapeutic Agent," Med. Record , 1905. No. 11, p. 411, corroborates the commonly accepted opinion that it causes an acceleration