H. F. Mueller1 of Vienna recently described certain small, round, colorless granules as constantly present in the fresh blood. These granules were regarded as entirely distinct from the blood plates. This observation did not seem at first to attract very much attention. In the last number of the Bulletin of the Johns Hopkins Hospital Wm. R. Stokes and Arthur Wegefarth publish an article from the Bacteriological Laboratory of the Health Department of Baltimore, in which they state that they have confirmed Mueller's observation, and in which they recite a number of very interesting experiments that appear to throw considerable light upon the much discussed question of the relation of the leucocytes to the bactericidal properties of the blood serum and to immunity.
Mueller described these bodies as small, round and colorless, about the size of the finest fat granules. They are highly refractile and show a dancing molecular movement,
ON THE PRESENCE IN THE BLOOD OF FREE GRANULES DERIVED FROM THE LEUCOCYTES, AND THEIR POSSIBLE RELATIONS TO IMMUNITY.. JAMA. 1898;XXX(4):223–224. doi:10.1001/jama.1898.02440560051006