29 



after a large number of transfers ; and in tLe following experiments I have 

 endeavoured to meet any objflctiona that might be made aa to the virulence 

 of my caltarps, by isolating B. alvei from a badly diseased hive and then 

 growing at once sufficient spores for the purposes of the experiment. Thus 

 but three transfers from a diseased larva were made ; aad all the spores used 

 in the following experiments were obtained in this manner : 



Two small hives, each containing strong healthy swarma, were selected 

 and placed side by side. 



Hive A was given spores of B. alvei in eyiup containing one-ihird of 

 a gramme of napthol B, to a litre of syrup 



Hive B was given spores of B. alvei in syrup containing from 1.6 to 1.8 

 c c. formic acid to a litre of syrup. 



The spores given were scraped from the surface of an agar slope culture, 

 put into 10 c c. of sterile water, and well shaken in order to obtain a good 

 suspension of spores. The water and spores were poured into medicated 

 syrup and the mixture thoroughly btirred. It was then given to the bees 

 and was readily accppted. This procedure was continued four days a week 

 for threp weeks, aod at the end of this time each hive had received the whole 

 of the growth from twelve sloped agar tubes. During the feeding period the 

 combs containing the brood were carefully examined, but none of the usual 

 symptoms of the disease appeared, although cultures were obtained from dif- 

 ferent parts of the hives and from the digestive tract of the workers. At the 

 end of three weeks the medicated syrup was discontinued for a week. Then 

 ordinary syrup containing spores was given, and at the end of ten days 

 typical symptoms began to be noticed, and after sixteen days the disease was 

 well establshed. Both hives, so far as I was able to judge, were the same — 

 no disease to be seen in either whilst medicated syrup was fed, but infection 

 manifest in both soon after the formic acid and napthol B. were discontinued. 

 This experiment goes to prove the benefit of feeding with syrup a substance 

 which is antiseptic and which hinders the germination of the spores. It also 

 confirms Lortet'd opinion that the digestive canal of tha nurse bee is alone 

 infected. I have never been able to obtain Cheshire's results, viz , the isola- 

 tion of the bacillus from the blood of the worker, but I have frequently found 

 it in the digestive canal of bees from diseased colonies. . 



From the results of the above experiments I conclude that in certain 

 cases the use of chemicals is beneficial, but I would not say that other meas- 

 ures, such as starvation and stamping out, should be abandoned as unneces- 

 sary or useless. Some of the drugs used are of very lit le, if any, value ; 

 but others, such as formic acid and napthol B , are undoubtedly very useful. 

 In some cases, especially those in which the disease is very viralent, it may 

 be advisable to resort to more drastic measures. 



Toxins. 



I endeavoured to find out whether or not the feeding of toxin (filtrate 

 from a two weeks old culture of B. alvei in f accharose bouillon) mixed in syrup 

 would enable healthy bees to withstand the disease. Small amounts of this 

 filtrate were given in syruo to a healthy colony every other day for three 

 weeks. The amount of filtrate fed was gradually increased, but as the 

 amount got larger the bees refused to take it, so it had to be poured over the 

 combs. At the end of three weeks spores of B. alvei, freshly isolated, were 

 fed, and symptoms ot the disease followed about fourteen days later. So the 

 toxin had little or no efltct, but further experiments are being made. 



