INFECTIOUS TRACHITIS 33 



Filtrability of the Granby Virus 



The larynx and trachea of both fowls which furnished the Granby virus 

 were triturated in a sterile mortar with sterile physiological saline solu- 

 tion. After permitting the mass to macerate over night in the ice Box, 

 the coarser particles were removed by filtering the fluid through sterile 

 gauze. Then the filtrate was divided into four parts. The first part was 

 forced through a sterile Berkefeld W filter, under an extra pressure ot'To 

 to 18 mm. of mercury, as measured by a manometer attached to a water 

 suction pump. The second portion was subjected to an extra pressure 

 of 10 to 12 mm. of mercury to force it through a Berkefeld N filter. The 

 third part readily passed a Berkefeld V filter under an extra pressure of 

 (j to 8 mm. of mercury. The fourth part was used as an unfiltered control. 



Berkefeld W Filtrate 



Three Plymouth Rock fowls were inoculated intratracheally on Xovem- 

 ber 28, 1929, with Granby infectious trachitis filtrate which had passed 

 through Berkefeld W filters. On January 2, 1930, the fowls were re- 

 inoculated with tracheal exudate from fowl MC 60840. The results are 

 given in Table 4. 



The fowls did not contract infectious trachitis when their tracheas were 

 swabbed with the filtrate of Granby virus which had passed through 

 Berkefeld W filters, but all three were afterwards found susceptible to 

 unfiltered Granby virus. Fowl 3000.5 died rather quickly after symptoms 

 appeared. A postmortem examination was made and not a lesion of any 

 kind could be found either in or on the body. This may have been ;i 

 toxemift form of infectious trachitis, as reported by Graham (1929). This 

 experiment indicates that the Granby virus did not pass the pores of the 

 Berkefeld W filters in sufficient quantities to cause infectious trachitis in 

 susceptible fowls. 



