20 Department Circular 28^, U. S. Dept. of Agriculture 



dull it will tear the comb, closiag many of the cells, so that the solu- 

 tion' can not enter. All honey cells that previously have not been ex- 

 tracted can be uncapped at the same time as the brood cells.- 



Several series of combs imcapped in this manner were treated with 

 both the alcohol-formalin and water-formalin solutions for 24 and 

 for 48 hours. In some of the 48-hour tests the cappings were cut 

 from only one side of tte combs, so that cultures for comparison 

 might be made from sealed cells at the same time and to obtain defi- 

 nite figures for the percentage of sterilization of the sealed cells. To 

 reduce the probable error arising from the missing of occasional cells 

 that would give growth, 5 open cells and 5 sealed cells from each 

 comb, instead of only 1, were cultured. In the 24-hour tests and in 

 the last 48-hour series only open cells were cultured, since from the 

 previous experiments it was found that 24 hours and in many cases 

 even 48 hours was not invariably sufficient to sterilize all sealed cells. 

 In tabulating these results the number of combs in each series of 

 samples and the total number of cells cultured is recorded, . 



As indicated in Table 7, a total of 281 scales from open cells of 

 combs treated for 48 hours in alcohol-formalin solution, including 

 the cells originally open and those opened by uncapping but exclud- 

 ing those washed after treatment, were cultured, none of which gave 

 any growth of BacUlus larvae. A total of 191 scales from 191 sealed 

 cells of the same combs (omitting 20 combs having perforations in 

 the " sealed " cells and other combs from which cultures were made 

 from open cells only) gave 115 cultures showing no growth of B. 

 larvae, 61 showing good growth, and 15 showing a few germinated 

 spores, or 75 positive cultures ; 39.8 per cent of these cells were there- 

 fore not sterilized. In the 24-hour tests of scales from open cells, 

 including all considered in Table 8 except those washed after treat- 

 ment, a total of 225 scales cultured gave 219 tubes showing no growth 

 of B. larvae, 2 showing good growth, and 4 showing a few germ- 

 inated spores, or 6 positive cultures, a percentage of 2.7 for open cells 

 not sterilized. Only one short (preliminary) series of scales from 

 sealed cells of combs treated for 24 hours was tested, with 2 out of 5 

 cultures showing growth of B. larvae. 



As indicated in Table 9, a total of 238 scales from open cells from 

 samples of combs treated for 48 hours in water-formalin solution,' 

 including cells originally open and cells uncapped, but no cells 

 washed after treatment, were cultured, none of which gave a growth 

 of Bacillus larvae. A total of 148 scales from sealed cells from the 

 same combs when cultured gave 103 showing no growth of B. larvae, 

 32 showing good growth, and 13 showing a few germinated spores, 

 or 45 positive cultures, a percentage of 30.4 for sealed cells not ster- 

 ilized. In the 24-hour tests of scales from similar open cells cul- 

 tured (Table 10), 220 scales were cultured, all the cultures showing 

 no growth of B. larvae. No 24-hour sealed cells were tested with 



" In a recent article Vincens W), who has charge of the station for apicultural research 

 of the Institute of Agricultural Research at Cagnes, France, describes his method for re- 

 moving cappings and soaking the contents of the cells previous to immersion in a water- 

 formalin solution. A Jet of water reduced to a spray is shot against the surface of the 

 comb at an angle with considerable force. This destroys or perforates the cappings and 

 fills the cells. After 12 hours the combs are again treated in like manner. Then after 

 passage through afl eortractor the combs, which are now thoroughly wet, are immersed 

 in a water-formalin solution containing only 10 per cent formalin for 24 hours, attec 

 which the solution is removed and the combs allowed, to dry. Vincens reports success 

 so far with this method used on a small scale. 



