During the course of a study of P/eiffer baciUi, strains were grown on special transparent agar and it was observed that when one particular strain was grown in this way two kinds of colonies developed. The colonies of one kind were like those usually described as typical for this organism while the colonies of the other kind were opaque and were very iridescent when viewed by oblique transmitted light. It was also observed that the organisms forming the colonies of one kind differed in morphology from the organisms forming colonies of the other kind (1). Further study indicated that the phenomenon was undoubtedly an example of variation or bacterial dissociation. During recent years much new and important knowledge concerning variations in bacteria of other species has been obtained (2) and it has seemed important to study in greater detail, in the light of this new knowledge, the variations occurring among the so-called influenza bacilli, or Pfeiffer bacilli.The bacteria of this group do no t form a well characterized bacterial species, and it has long been recognized that individual strains differ from one another in morphology and virulence, in the appearance of the colonies which they form, in their ability to form indole, in power to ferment sugar and to induce hemolysis, in their immunological reactions, and even in their requirements for g~owth in artificial cultures. The literature relating to the biological characteristics of the bacteria forming this heterogenous group has been recently reviewed by Jordan

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The influence of living Bordetella pertussis on the induction and duration of pathophysiological reactions in mice infected intranasally with graded doses of culture was studied. Lethally infected mice showed loss of body weight, spleen atrophy, pronounced hypothermia and hypoglycemia, and highly elevated levels of leukocytes and serum immunoreactive insulin. Sublethally infected mice showed normal weight gain, practically normal temperature, spleen enlargement, lesser pronounced hypoglycemia, lower but significantly elevated levels of leukocytes and serum immunoreactive insulin, and histamine sensitization. Intensity of each reaction was related to the degree of lung infectivity. Hypothermia and leukocytosis were highly correlated. Concentration of serum immunoreactive insulin was closely related to the level of leukocytosis but not to the level of glucose. The strain and age of mice significantly affected the degree and duration of the reactions. The results suggest that the intranasally infected mouse may provide a useful model for investigations on whooping cough.

During a field investigation of acute conjunctivitis in the lower Rio Grande Valley of Texas bacteriological cultures were made from more than 100 cases. Bacteria of the genus Hemophilus, apparently the main cause of the infection, were isolated from the conjunctiva of approximately one-half of the cases. Some strains were readily identified as Hemophilus influenzae. The majority, although resembling H. influenzae in some respects, were found to be different from it and to be like the so-called Koch-Weeks bacillus described by early investigators (Koch, 1883; Weeks, 1886, 1887; and others). The relation of the Koch-Weeks bacillus and H. influenzae has been the subject of much controversy and the two have been grouped as one species by many workers. In this paper the characteristics of the Koch-Weeks bacillus and ways of separating it from H. influenzae will be presented.

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In this communication, further evidence has been given which supports the view that the majority of the strains of Hemophilus influenzae giving rise to meningitis are of the same serological type. Forty strains have now been examined, and thirty-seven have been of Type b. A horse has been artificially immunized with Type b strains isolated from the spinal fluid of patients. By precipitation tests with the capsular carbohydrate, the serum has been shown to be highly typespecific. For the first 3½ months of immunization, the type-specific antibody content of the serum increased steadily. Later, in spite of continued immunization, there occurred no apparent increase. By means of animal inoculations, it has been shown that the anti-serum has an anti-infectious action. If mice, inoculated intraperitoneally with Type b organisms, were also given serum, the bacteria did not invade the blood, or did so to only a limited degree. But the recovery of the treated mice was found to be inconstant. In rabbits infected intravenously and later treated by the same route, the number of bacteria in the blood stream was quickly reduced and sterilization followed. In the experiments it was necessary that the dosage of the culture be not too large, as influenza bacilli contain a substance which, artificially introduced into mice and rabbits, gives rise to marked toxic reactions. This substance is apparently not neutralized by the antiserum. However, it was found that among the surviving animals, those treated with immune serum returned to the normal state more quickly than did the animals not so treated. The anti-infectious action of the serum has further been demonstrated by a study of its effect on the lesions which follow inoculations of type-specific bacteria into the skin of rabbits. Again it was found that for any effect of the serum to be manifested it is necessary that the dosage of bacteria be limited, since if large numbers of bacteria are introduced into the skin the development of lesions cannot be completely inhibited, no matter how large doses of serum are employed. As the number of living S organisms which cannot be neutralized is roughly equivalent to the number of R or heat-killed bacteria which may produce a lesion, it seems that there is some preformed irritating substance in the bacterial cells which may give rise to lesions, even if the bacteria are killed or inhibited in their growth. In order to demonstrate the protective action of immune serum, therefore, it has been found necessary to employ a dosage of culture so small that if the bacteria are immediately killed, or their growth inhibited, no lesion results. Employing immune serum under these conditions, it has been found that the ability of the serum to prevent the occurrence of skin lesions has progressively increased with continuing immunization of the horse. A series of eighteen patients suffering from influenzal meningitis has been treated with Type b antiserum. Following the use of serum, recovery occurred in one patient of the series, and in two, although the patients ultimately died, the spinal fluid cultures became sterile and remained so for periods of 7 to 14 days. In four other cases, the spinal fluid cultures showed, temporarily, either no growth of bacteria, or a reduction of their number. Among five patients in whom septicemia was present before treatment, in four the blood cultures, after treatment with serum, became sterile. The number of patients treated has been small, and the treatments were carried out under widely varying conditions. It is difficult, therefore, to draw conclusions regarding the actual value of this form of therapy, or the best methods of procedure. The clinical results, however, indicate, as do the experimental, that the serum has a definite anti-infectious action. The experience is too limited to permit final conclusions regarding the importance of the addition of fresh (complement-containing) serum to the immune serum. Further experience, under more accurately controlled conditions, may show that the serum has greater practical value in treatment than is shown by the mortality results in this series of cases.

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