40 



MASS. KXI'KHI.MKNT STATION' BUIT.ETIN 273 



of tiie four pullets so treated contracted the disease and died. The re- 

 sults of this transfer appear in Table 9. .'\n attempt to inoculate chicken 

 MA 94420 with virus from chicken L 34, as recorded in Table 10, was 

 futile, for MA 94420 did not take the disease. The Leverett infectious 

 trachitis virus tended to produce a chronic form of the disease which 

 was not easily transmitted to healthy chickens under laboratory condi- 

 tions. 



Two attempts were made to transmit Westwood virus. In the first 

 experiment nine healthy fowls were inoculated on February 26, 1930, with 

 tracheal exudate from two Westwood fowls showing clinical symptoms of 

 infectious trachitis. Four of the inoculated birds developed mild, non- 

 fatal cases, and five did not react at all. 



The next chronic field virus tried out in the laboratory came from 

 Gardner on March 15, 1930. An attempt was made to transmit the in- 

 fection to healthy birds under laboratory conditions. With this object 

 in view, four cockerels and six pullets were treated intratracheally with 

 exud"ate from the tracheas of the fowls sent in. Also the livers, spleens, 

 and kidneys showing lesions of infectious trachitis were fed to the cock- 

 erels and pullets. Table 9 shows that four of the birds remained well 

 throughout the experiment, three had mild chronic cases with cough and 

 pseudomembrane in the larynx, and three developed acute symptoms of 

 disease. One of these three, MA 94470, died. 



An attempt to transfer the disease from the three acute cases is record- 

 ed in Table 10. There were no fatal results, although chicken MA 94473 

 contracted the disease in a mild form. The final virus was lost in an 

 attempt to transfer it from MA 94473 to MA 94469. 



Three fowls having chronic infectious trachitis were sent in from Sout!\ 

 Lincoln on April 30, 1930. Two fowls, three cockerels, and three young 

 chickens were treated intratracheally with this virus and no reactions oc- 

 curred. The virus had apparently lost its virulence, although the fowls 

 sent to the laboratorj' were suffering from severe chronic tjpes of in- 

 fectious trachitis. 



The last infectious trachitis virus mentioned in Table 9 was called the 

 Watertown virus because it was found in a flock of laying hens at Water- 

 town. Seven chickens about a month old were placed on this experi- 

 ment. All of the chickens remained well, demonstrating once more that 

 it was not always possible to successfully inoculate healthy birds witTi 

 infectious trachitis virus from old chronic cases of the disease. 



Table 10. — The second transfer of virus froim chronic field cases. 



Result 



Leverett. 

 Gardner. 



None 



None 

 None 

 Mild 



