32 BULLETIN 431, TJ. S. DEPAETMENT OF AGEICULTTJBE. 



METHODS USED IN MAKING EXPERIMENTAL INOCULATIONS. 



The laboratory study of bee diseases being new, it has been neces- 

 sary in many instances to devise new methods. In the experimental 

 inoculations of bees the methods used have undergone revision from 



time to time. Those 

 now employed have 

 proved quite satis- 

 factory. 



As the virus of sac- 

 brood has not been 

 cultivated in the lab- 

 oratory artificially, it 

 has been necessary in 

 these investigations 

 to inoculate a large 

 number of colonies. 

 A nucleus of bees 

 that could be accom- 

 modated on from 3 

 to 6 brood frames 

 was found to serve 

 very satisfactorily 

 the purpose of an ex- 

 perimental colony. 

 The queen should al- 

 ways be clipped. The 

 frames are placed in one side of a 10-frame hive body (fig. 28). Over 

 the entrance to the hive is placed wire cloth, leaving a small space 

 of about 1 inch in length on the side occupied by the brood frames. 

 Petri dishes * (fig. 29) serve well the purpose of a feeder. Both 

 halves of the dish are used 

 as receptacles. These are 

 placed, preferably about 

 four of the halves, within 

 the hive on the bottom 

 board on the side not occu- 

 pied by frames. The hives 

 of the experimental apiary 

 (PI. Ill) are arranged 

 chiefly in pairs, with the entrances of consecutive rows pointing in 

 opposite directions. The space occupied by the apiary should be 



' A Petri dish, a much-used piece of apparatus in a laboratory, is simply a shallow, circular, glass dish 

 with a flat bottom and perpendicular sides. It consists of two halves, a bottom and a top. These are 

 very similar. The top half, being slightly larger, fits over the bottom one when the two halves are placed 

 together. 



Fig. 28.— The hive as it is employed to house and feed a colony used 

 for experimental inoculations. Here are shown four Hoffman 

 frames, a division board, four open Petri dishes as feeders, and the en- 

 trance nearly closed with wire cloth, the opening being on the side 

 of the hive body occupied by the colony. The dimensions indicated 

 are approximate. The angle at which the hive was photographed 

 for this drawing caused its length to appear foreshortened. ( Original. ) 



Fig. 29.— Petri dish. The top half is slightly raised. Tliosa 

 used here are 4 inches in diameter. (Original.) 



