To the Editor:
—The recent criticism directed to certain studies that I have published during the past five years (Am. Rev. Tuberc. 19:18 [Jan.] 1929) on the recovery of the virulence of B C G deserves a reply. These studies can be summarized in a few sentences: 1. If the original culture from the glycerinated potato-bile or Sauton medium is inoculated intravenously or intraperitoneally in doses of from 1 to 5 mg., a small number of the animals—from 2 to 5 per cent—will develop visceral lesions that cause the death of the animal if sufficient time is allowed. The disease could be passed through a series of animals. 2. I have successfully dissociated several B C G cultures that were obtained from various sources into R, which was nonvirulent, and S, which was virulent for guinea-pigs.The first observation is in accord with that reported by Watson (J. Am.