In view of the results obtained in the last experiment, in which it was shown that hams may become infected from the use of ham thermometers, it seemed not improbable that hams might also become infected from the pumping needles, which, like the thermometers, are thrust deep into the bodies of the hams beside the bone. In order to throw some light upon this point, cultures were taken from the grease and dirt that accumulate on the shields at the bases of the pumping needles, as such material must undoubtedly be carried into the hams at times on the needles. The ham-souring bacillus was found several times in these cultures, and hence it is fair to infer that hams may also become infected at times from the pumping needles, just as they become infected from the thermometers. Bits of contaminated meat and grease and particles of dirt carried in on the pumping needles would be forced out into the hams by the pumping pickle, which passes out through small openings or fenestræ in the needles, and this probably affords one explanation as to why so many more body sours occur in the mild-cure hams. In the mild-cure hams, which are pumped in the shank only, the pumping needle is introduced near the femorotibial articulation, and the shank is saturated at the start with a strong brine solution, while the body of the ham is not. If the ham-souring bacillus were carried into these hams on the pumping needle, the growth of the bacillus in the shank would be inhibited by the strong brine solution with which the shank is saturated, but there would be nothing to prevent the bacillus from growing upward into the body of the ham, which has not been pumped and is free from pickle. This would also explain the fact that the souring often starts at the knee joint and extends upward into the body of the ham. In the case of the regular cure hams, where the ham is pumped in both body and shank, the entire ham is more or less saturated at the start with the strong brine of the pumping pickle, which tends to inhibit the growth of the ham-souring bacillus even if this bacillus should find its way into these hams on the pumping needles. It is in the mild-cure or partly pumped hams, where the body of the ham is left unpumped, that the ham-souring bacillus finds its best opportunity for development, and the greater proportion of the sours that occur in the packing house are found in these hams.