About the close of 1892 I examined bacteriologically some cases of othæmatoma, with a view of ascertaining if there was any basis for the idea which occurred to me, and which I mooted in an article in the “Journal of Mental Science” for April, 1893, that that condition was the result of bacterial activity. In none of the cases examined was there a history of injury. In the first two (an adult imbecile and a chronic maniac) cover-slip preparations of the extravasated blood—taken with full precautions as regards cleanliness—showed staphylococci, singly, in twos, in fours, and in small groups. In size the cocci resembled closely S. pyogenes aureus or albus. An attempt to cultivate the organism on gelatine and broth failed; unfortunately no agar was at hand. In the light of subsequent experience, I believe that this failure may, with much probability, be attributed to the fact that the amount of material transferred to the culture-tubes was too small. Several drops of the sero-sanguinolent extravasate should be taken for each tube. In the third case (that of a dement) what appeared to be the same organism was found in the cover-slip preparations and grown upon broth and altogether like that of a cultivation of S. pyogenes aureus. In other tubes, however, the growth remained white throughout, so that S. pyogenes albus was present as well.