128 EIGHTEENTH ANNUAL REPORT OF THE 



It perhaps will be well, however, for me briefly to review a few 

 points, in order to connect it up with some of the conclusions that I 

 want to draw later on. 



First, as to the age of the larvae affected by this disease. As you 

 know, it is a disease which affects the larvae and kills it when it is 

 between three and four days from the hatching of the egg, very much 

 younger than the other diseases. It first turns a light yellow color, 

 gradually getting darker, or it may be a gray color, gradually getting 

 darker, depending upon the particular bacteria which are present in 

 the diseased mass. And that I think is a point which should be dealt 

 with just a little bit. 



You know that there is a tremendous variation in the appearance 

 of larvae attacked by European foul brood. With American foul 

 brood, why, if you see one lot of it, you know what it all looks like, 

 because it is practically always the same, and when the larvae die 

 they form a peculiar position in the cell and are practically all alike. 

 With European foul brood, on the other hand, we find tremendous 

 variability in the position of the larvae, and in their color and whether 

 or not they have an odor, and whether or not they show any tendency 

 to ropiness, and all those things. We have recently found out why 

 there is this variation, and while it is not especially important to bee- 

 keepers to know this in connection with the treatment, it does help to 

 elucidate a good many points, if we know what brings this difference 

 about. 



As you probable all know, European foul brood is caused by a 

 bacteria which we call bacillus pluton. It is the cause of the disease, 

 and it is always present in the disease, and there can be no European 

 foul brood without the presence of bacillus pluton. But there are 

 also found in those larvae dying of European foul brood a number of 

 other bacteria, not the cause of the disease, but they are a common 

 occurance as accompanying the disease. One of the most common of 

 these is the bacillus alvei. If that is present in larvae dying of Europ- 

 ean foul brood, as it very commonly is, the color, instead of being a 

 brilliant yellow, usually is gray. 



Now, the4arvae dying when there is only bacillus pluton present, 

 if you put a match or a toothpick into it and pull it out slowly, it 

 practically ck^es not rope at all, it breaks right off, unless it is very 

 watery. While in the moist stage, it may run down over the cell, but 

 if it is begmning to harden up it will break off. If bacillus alvei is 

 present, wif sometimes get a ropiness in European foul brood of an 

 inch or aniach and a half, and rarely two inches. So that it is different 

 in appearance and different in color. The difference in ropiness is due 

 largely to the presence of an intervening bacterium, which does not 

 cause the death of the larvae, does not cause anything in the disease, 

 except what] seem clearly symptoms. 



Now, Another point which has been a great deal confused in the 

 minds of bee-keepers in this country, as to whether or not European 

 foul brood has an odor. Some bee-keepers have maintained, and 

 maintain very vigorously, that there is practically no odor in European 

 foul brood. But when bacillus alvei or any of the three or four other 

 bacteria which are sometimes present in this disease find their way into 



