1.No multiplication of acid-fast bacteria has been observed in our cultures of rat leprosy in minced embryonic (foetal or neoplastic) tissues suspended in Tyrode solution.
2.An acid-sensitive, but facultative acid-fast and pleomorphic organism did grow in certain of these cultures. This type of organism is identical with that repeatedly cultivated by us and others from human and rat leprosies in other media.
3.The minced embryo medium appears to be less suitable than a leaner medium for the growth of the cultivable organism from leprosy.
4.It is suggested that the diverse cultural results with embryonic tissue medium reported by other authors may be due, on the one hand, to the great number and serial transfer of acidfast bacteria of the inoculum; and, on the other hand, to the interpretation of the acid-sensitive organisms appearing in the cultures as contaminants.