PNEUMOCOCCAL hyaluronidase has been shown to hydrolyse only the glucosaminidic bonds of hyaluronate1. The pneumococcal enzyme and other bacterial hyaluronidases have further been shown to differ from hyaluronidases of animal origin in their thermal lability, and in their capacity to hydrolyse hyaluronate faster and more completely. The main product of exhaustive hydrolysis of hyaluronate by testicular hyaluronidase is a tetrasaccharide2, whereas the end-product of the action of pneumococcal hyaluronidase is a fraction having the reducing values of a disaccharide1.