Abstract
In the present investigation we studied a parasite of red blood cells in the amphibian Hydromantes italicus. The parasite, a globular microorganism having a diameter of 0.25 to 0.3 mum, was found in large numbers in vacuoles of red blood cells. As seen by electron microscopy, it possesses no cell wall and has the morphological appearance of a mycoplasma. The parasite has great motility by mechanisms not yet elucidated. It is possible to transmit the infection experimentally from infected to healthy amphibians. Culture of the microorganism, named Chondrostagon haematicum, in artificial media has not yet been successful.