SACBROOD. 



29 



In the study of the virus of sacbrood use has been made also of 

 the Pasteur-Chamberland filter * (fig. 27). This is a clay filter, the 

 pores of which are much finer than those of the Berkefeld used. In 

 using this filter, an aqueous suspension of larvse dead of the disease 

 is prepared as before. This is filtered by the aid of pressure obtained 



Fig. 27.— A convenient apparatus which, can be employed in using the Pasteur-Chamberland, 

 Berkefeld, and other filters. Pasteur-Chamberland filter (b) with a glass mantle (a), a rubber stopper (c) 

 through which passes the filter, a connecting rubber tubing (d), glass tubing (e), a perforated rubber 

 stopper (f), a vacuum jar (g), designed by the writer, in which is placed a cotton-stoppered and steril- 

 ized flask, a glass stopcock (h), a vacuum gauge (i), a reservoir (m) with pressure-rubber connections 

 (j), and a vacuum pump (k). (Original.) 



by means of a partial vacuum in an apparatus devised for this pur- 

 pose. Filtrates obtained from this filter when fed to healthy colonies 

 produced the disease. Since the virus of sacbrood will pass through 



a The Pasteur-Chamberland filter consists of clay molded in the form of a hollow cylinder and baked. 

 This is used with a glass cylinder (a) fitted with a rubber stopper (c). In the use of this filter, force is 

 employed. This was obtained for these experiments through the use of a jar (g) devised by the writer in 

 which a partial vacuum can be produced. In this jar, is placed a flask plugged with cotton and sterilized. 

 Connections are made as shown in the illustration, the vacuum being produced through the use of the 

 pump (k). In less than half an hour usually a half-pint of nitrate can be obtained with this apparatus. 



