Log phase cells of Micrococcus lysodeikticus (luteus) IFO 3333 autolyzed when incubated at 37 C in 0.01 M sodium-phosphate buffer pH 7.5. The enzyme involved in the autolysis was recovered mainly in an aqueous phase from cytoplasmic membranes and cytoplasmic materials treated with n-butanol, and proved to be an N-acetylmuramyl-L-alanine amidase. The autolysis of log phase cells suspended in autolyzing buffer was depressed by the addition of trypsin to the buffer.

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The log phase cells of autolytic Micrococcus lysodeikticus (luteus) IFO 3333 did not autolyze when grown in the presence of trypsin although the growth curve and morphology of the cells were not influenced.
A non-autolytic mutant was obtained by subculture of the wild-type strain IFO 3333 on an agar slant containing 1% glucose. The mutant (strain MT) was arranged in tetrads or in clusters consisting of regular tetrads, in contrast to the wild-type IFO 3333 which occurred singly or in irregular masses. The mutant MT grown in a culture medium containing trypsin caused remarkable alteration in cell morphology : large cell packets consisting of a number of “unit tetrads” arranged regularly in three dimensions were formed by the addition of trypsin to the medium. The findings suggest that inhibition of the separation of divided cells is brought about by inactivation or suppression of a cell wall autolytic enzyme which plays an important role in the separation step and is accessible to externally added trypsin in the mutant cells but not in the wild-type cells.
The possibility that there are two kinds or phases of autolytic enzymes, “a physiological autolytic enzyme” and “a useless autolytic enzyme”, is discussed.

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Cross immunofluorescence revealed that coxsackievirus A 16 (CA 16) shared a common antigen with enterovirus 71 (E 71). The cross reactivity of these two serotypes was also examined by complement fixation test with purified virus preparations fractionated by sucrose density gradient centrifugation and two peaks of antigenicity were detected, one being type-specific and the other cross-reacting. The common antigen was heat-stable and attributable to empty capsids. Immunodiffusion also revealed the common antigen. Infants without antibody to E 71 developed complement fixing and precipitin antibody to E 71 after recovery from hand, foot and mouth disease caused by CA 16.

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A method for quantitative extraction of extravasated dye from the skin was studied in guinea pigs and rats. A simple method with a low cost and good recovery was established as follows; A piece of the skin containing extravasated dye was soaked overnight in a stoppered glass tube containing 1 ml of 1 N KOH at 37 C. Then, 9 ml of a mixed solution of 0.6 N H₃PO₄ and acetone (5:13) was added to the tube. The tube was shaken vigorously for a few seconds and centrifuged at 3, 000 rpm for 15 min. Absorbance of supernatant was measured at 620 nm. The recovery rate of the dye was about 95% both in guinea pigs and rats.
Using this method we observed that fasting stress significantly reduced the intensity of skin reactions induced by chemical mediators, heterologous PCA and especially homologous PCA in guinea pigs.

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