“As regards penetrability, no claim has ever been made for Trimethol in this connection; and, as I pointed out in my original paper (_American Medicine_, September, 1914), when referring to the independent tests made by Dr. Frederick Sondern, ‘No attempt was made to determine the bacterial content of the solid particles, as in the opinion of the writer sterilization of the interior of these particles is not only absolutely impossible, but wholly unnecessary. The fact of the fluid contents of the canal being sterile may be taken to indicate that the exterior of all solid particles is in a like condition, and therefore harmless. It is the organisms in the fluid portions only that produce the deadly effects through the chemical substances they secrete; those in the interior of the solid portions (_i. e._, as evacuated) may be disregarded, as they are not available for good or evil.’ “I must confess to no little surprise on learning that your investigator is still using the Hygienic Laboratory method of determining phenol coefficients. I would respectfully suggest that you call his attention to the critical comparison of the Hygienic Laboratory and R.-W. Tests, which he will find in the enclosed reprint from the _New York Medical Journal_ of March 11, 1916: ‘Instead of being an improvement upon the standard R.-W. Test, the so-called Hygienic Laboratory Method is so defective as to be wholly unreliable, and incapable of furnishing results of any scientific or practical value whatever.’” As to the statement that the potent constituent of Trimethol Tablets and Trimethol Syrup is not fully available as a bactericide until it comes in contact with the pancreatic fluid, attention is called to a leaflet, which accompanies each bottle of Trimethol Syrup, that reads: “Trimethol is insoluble in water, but when properly emulsified has a Rideal-Walker co-efficient of 40; that is to say, it is 40 times more efficient as a germicide than phenol (pure carbolic acid).” The Trimethol Syrup which was used in the investigation, when mixed with water produced an almost perfectly transparent solution, which justifies the assumption that the proper physical conditions were observed and that this objection is not well founded. As regards the relation of pancreatic fluid to bactericidal availability of Trimethol, there is little to say, other than that the published statements in the advertising accompanying the packages make no mention of this point. It would be interesting to know what, if any, relation the pancreatic fluid has to this substance, in view of the statement that it “has a Rideal-Walker coefficient of 40.”