70 THE INFLUENZA BACILLUS. 



The projections of the pollen-grains of the Bean facilitate their 

 removal by bees. The grains are not easily shaken out of their 

 pollen-sacs, are somewhat sticky, and are produced in, compara- 

 tively speaking, very small quantities. 



^be 3nflueti3a Bacillue/ 



THE discovery of the germ of Influenza, first by Dr. R. Pfeiffer, 

 and shortly afterwards by Dr. Canon, was announced on 

 January yth, at Koch's Institute, Berlin. Dr. Pfeiffer 

 examined the sputum of Influenza patients, first sterilising and 

 cleansing it by Koch's methods, and then treating it with ZiehFs 

 solution or Loefifler's hot methylene blue. A large number of 

 micro-organisms then became visible under the microscope, and it 

 soon appeared that they were mostly of the same kind. This was 

 always the case with the sputum of patients suffering from Influenza 

 alone ; when the disease was accompanied by other pulmonary 

 disorders other bacteria were also present. It was intelligible that 

 this bacillus had so long escaped detection, for it was far smaller 

 than any micro-organism hitherto known, and the circumstance 

 that its two extremities stained more intensely than the intervening 

 parts gave them a striking resemblance to diplococci and stepto- 

 cocci. Pure cultures of the bacillus were cultivated. The colonies 

 were so small, that at first they were only visible under a magnify- 

 ing glass. Glycerine Agar proved the best nutritive medium. 

 One of the characters of the bacillus was its immobility, the 

 colonies not flowing together, but remaining separate. Monkeys, 

 rabbits, guinea-pigs, rats, pigeons, and mice, were inoculated, but 

 Influenza was only produced in the first two. Dr. Canon's method 

 was to examine under the microscope blood from Influenza patients, 

 taken during fever. Organisms hitherto unknown were found. 

 Special attention was attracted to them, as they were found only in 

 the case of feverish influenza patients and disappeared from the 

 blood as soon as recovery took place. The examination of his 

 discovery by Drs. Koch and Pfeiffer showed the bacillus to be 

 identical with Pfeiffer's. 



* The Lancet^ 1S92, Vol. I., pp. 169 — 170. 



