16 Department Circular 28i, U. S. Dept. of Agriculture 



with aseptic precautions placed in a number of these glass cells, and 

 cappings were sealed on the open ends as in the previous experiment. 

 The sealed glass cells were then submerged for 48 hours in alcohol- 

 formalin and water- formalin solutions, after which they were al- 

 lowed to dry for a few days. Observations made at the end of 48 

 hours showed that no perceptible quantity of liquid had entered the 

 cells. Enough moisture had been absorbed through the cappings, 

 however, possibly in the form of vapor or of an indistinguish- 

 able film, to cause the dried scales to become slimy or almost ropy, 

 like diseased remains before they have dried down. After drying, 

 cultures were made in the usual manner {Table 6). Three scales 

 out of 20 so treated, 1 in alcohol-formalin solution and 2 in water- 

 formalin solution, apparently were completely sterilized, and from 

 several, most of which had been treated in the alcohol-formalin solu- 

 tion, cultures were made which showed only a comparatively few 

 germinated spores and having a slight growth. This seemed to in- 

 dicate that not much actual disinfectant gains access to some at 

 least of the sealed cells. 



Table 6. — Cultural results of various tests vnth spores of Bacillus larvae 

 inclosed i/n artificial glass cells, capped, and treated for 48 hours w formalin 

 solutions 



1 All showing few spores germinated; one very few. 

 « Two showing many spores germinated. 

 > One showing very few spores germinated. 



VACUXJM TREATMENT 



A method of forcing disinfectant solution into the cells was de- 

 vised to demonstrate whether alcohol fills all spaces in a submerged 

 comb. Pieces of comb of the same size as those used in previous 

 experiments and containing numerous sealed ceUs were cut from 

 infected brood combs and submerged in 180 cubic centimeters of 

 disinfectant solution in graduated cylinders. One of these was 

 allowed to soak for 48 hours. The cylinder containing the sub- 

 merged comb was then subjected to a vacuum of 28 inches, which 

 caused the air still remaining in many of the open cells to rush out 

 in considerable amount and the air in sealed cells to bubble through 

 and in some cases to burst the cappings. When the pressure was 

 allowed to become normal the free liquid in the cylinder had de- 

 creased by from 25 to 30 cubic centimeters in displacing the air in 

 the cells. Similar results were obtained by applying the vacuum 

 as soon as the combs were immersed. When combs so treated were 

 subjected to a vacuum again after 48 hours' immersion they were 

 found still to release a few air bubbles from sealed cells. These ex- 

 periments made it evident that even in open cells of combs immersed 

 for 48 hours at ordinary atmospheric pressure a considerable por- 



