1. Studies of the cultivation of the virus of common cold in tissue medium, and the capacity of the culture virus to induce infection in human volunteers are reported. 2. Detailed descriptions are given of the methods employed to isolate the virus, preserve and cultivate it, and to test its activity in human volunteers. 3. The virus of common cold can easily be isolated from properly selected patients and cultivated in tissue medium. 4. When kept in the original nasopharyngeal washings, the virus will survive at ice box temperature under anaerobic conditions for at least 13 days. 5. If the nasopharyngeal washings are frozen and dried in vacuo , the virus retains its activity for at least 4 months. 6. The virus of common cold has been proven to multiply in medium containing chick embryo tissue. Such cultures retain their capacity to produce typical infections in human beings for many transfers involving a period of several months. Attempts to cultivate the virus have been successful in seven out of eight instances. 7. Prolonged cultivation of the virus in tissue medium eventually leads to a loss of activity. 8. Strains of virus under cultivation maintain their potency best when transfers are made at 2 and 3 day intervals. 9. After removal from the incubator a culture of virus rapidly becomes inactive whether it be kept under seal in the ice box or frozen and dried in vacuo . 10. The destructive action of the medium can be prevented if the culture is mixed with gum acacia before freezing and drying in vacuo .
1. Evidence is presented indicating the presence of a filtrable virus in the nasopharyngeal secretions of individuals suffering from influenza. 2. An attempt to transfer influenza from one human being to another by means of filtered nasopharyngeal washings resulted in the production in the inoculated volunteer of a common cold. 3. A filtrable agent has been cultivated in tissue medium from the filtered nasopharyngeal washings of patients with influenza. 4. Inoculation of the cultivated virus into human volunteers results for the most part in the production of a severe common cold with a tendency to pronounced constitutional reaction. 5. In one instance following inoculation of culture virus an infection clinically resembling influenza has been produced. 6. The more closely the source of the virus approached the type of epidemic influenza, the more likely the virus was to provoke constitutional symptoms. 7. The presence of certain pathogenic bacteria in the upper respiratory tract of inoculated individuals was not observed to modify the course or character of the experimental infection. 8. On prolonged cultivation the virus loses the capacity to infect human volunteers.