_Other Hemophilic Bacteria._—The question of a pseudo-influenza bacillus was first raised by Pfeiffer and has been studied by many workers after him. Grassberger, who carefully investigated this problem, worked more particularly with two strains showing the extreme of variation between the small characteristic morphology of the B. influenzæ and the thread forms supposed to be characteristic of the so-called pseudo-influenza bacillus. The great majority of workers have agreed with him in concluding that this morphological variation is not sufficient nor constant enough to justify separating two such groups. Nevertheless many reports indicate peculiar tendencies of certain strains toward thread formation. There seems to be suggestive evidence that the organism described by Cohen in 1909 under the name B. meningitidis cerebrospinales septicemicus is different from true B. influenzæ. Although the cultural characters were apparently identical, this organism was definitely pathogenic for guinea pigs and rabbits. The involvement of joints in the cases reported by Longo and others would suggest a greater pathogenic power for these strains. Prasek and Zatelli reported a similar bacillus from meningitis, and Davis found that his meningitis strains were more pathogenic for rabbits than were others. Wollstein has studied this question very carefully and found a marked difference between the strains from the meninges and those from the respiratory tract in their pathogenicity for rabbits. The strains with a tendency to thread formation were usually also those grown from the meninges, but she concluded from the results of serological tests that all strains of B. influenzæ are of one race, irrespective of their origin or virulence. The question is still an open one, as Batten and others described strains from the meninges which are non-pathogenic, and Ritchie found his strains from meningitis pathogenic for guinea pigs but not for rabbits. The irregularity and wide divergence in the results of blood cultures may have a definite relationship to these differences in the pathogenicity of strains. Other hemophilic bacteria include the bacillus described by Friedberger under the name of B. hemoglobinophilus canis. This organism is to be found in the preputial secretion of dogs. It does not show the phenomenon of symbiosis, and I have found that it grows rather more freely and is more resistant to drying than is the influenza bacillus. Krage has confirmed Friedberger’s findings growing this bacillus from 60 per cent. of his dogs, and believed it a pyogenic organism just as B. influenzæ may be.