May, 1922 



GLEANINGS IN BEE CULTURE 



299 



teria which cause so much confusion. Bac- 

 teria are extremely small micro-organisms, 

 the smallest members of the plant kingdom. 

 They are simple, single-celled plants which 

 grow and increase in numbers by continu- 

 ally dividing in two. This often takes 

 place rapidly under proper conditions of 

 food supply and temperature. Certain pa- 

 thogenic or disease-producing bacteria are 

 known to be the cause of various diseases 

 of plants and animals. These attack only 

 living tissues, as a rule. Others known as 

 putrefactive or decomposing organisms have 

 only the power of decomposing plant or ani- 

 mal tissues after death has occurred, acting 

 like scavengers, breaking down and destroy- 

 ing the dead tissues. 



Some bacteria have the power of form- 

 ing what are known as spores. These are 

 formed when conditions develop unfavor- 

 able for growth, the purpose being to carry 

 the organism thru this unfavorable period 

 until it can find again the proper growth 

 conditions. The spores have thick walls 

 wliich enable them to resist long drying or 

 high temperatures and to pass thru long 

 periods without food. When spores at any 

 time are placed where food and other con- 

 ditions are again favorable for growth, they 

 germinate and become active once more, in 

 something the same way that seeds sprout 

 on planting. 



There is another type of bacteria which- 

 never forms resting-stage spores. They al- 

 ways occur only in what is known as the 

 vegetative or actively growing stage. These 

 are like already growing plants that may 

 be transplanted to another spot. When con- 

 ditions become unfavorable for the growth 

 of non-sporeforming bacteria they gradually 

 die off. In the case of bee diseases we 

 have to deal with all these various types 

 of bacteria. 



The Cause of European Foul Brood. 



European foul brood will be considered 

 first, since it responds more freely to ex- 

 ternal influences affecting the disease. It 

 is also the worst offender regarding varia- 

 tions in symptoms. The appearance of the 

 symptoms varies to such an extent at times 

 as to cause confusion while, as will be seen 

 later, American foul brood is much more 

 constant in the manifestation of its symp- 

 toms. The explanation lies in the fact that 

 in the case of Europeon foul brood there 

 are associated with the bacteria causing the 

 disease several varying types of organisms, 

 while in American foul brood there is but 

 one organism active, as will be described 

 later. 



As is well known a specific organism. Bac- 

 illus pluton, is the cause of European foul 

 brood. The organism is presumably fed to 

 the young coiled larvae in their food, pri- 

 marily from some outside source. It at 

 once starts to grow in the larval intestine, 

 increasing quite rapidly in numbers. This 

 rapid start or short incubation period is pos- 

 sible because BacillKs plutoii is always in its 

 active growing or vegetative stage. It does 



not form spores, and consequently is ready 

 to attack at once without the lapse of time 

 necessary for spore germination. As the 

 disease develops and the bacteria causing 

 the disease increase in numbers, they give 

 off toxins which are absorbed by the larva 

 and eventually cause its death. 

 Relation of Secondary Invaders to Confus- 

 ing Symptoms. 



There are found associated with Bacillus 

 pluton other varying organisms known as 

 secondary invaders. They never cause the 

 death of the larva, which distinguishes them 

 from the primary pathogenic organism. 

 They are either present in small numbers 

 or get into the larva soon after death and 

 start to develop in the dead larva. In the 

 early stages of the disease both in the larva 

 and even in the colony as a whole, the sec- 

 ondary invaders generally have little effect 

 on the appearance of the symptoms. Most 

 of these do not have the power of decompos- 

 ing animal tissues to any extent. Bacillus 

 pluton, with other not actively putrefactive 

 organisms, predominates in numbers and un- 

 til after the death of the larva occurs is 

 found only inside the larval intestine. When 

 external conditions are such that the disease 

 is allowed to run unchecked for some time, 

 then other secondary invaders developing 

 more rapidly come into prominence, and or- 

 ganisms with purely putrefactive or decom- 

 posing functions begin to invade the entire 

 body tissues of the larva. Therefore it has 

 been found that, as the secondary invaders 

 vary in character and prominence, so the 

 symptoms vary from the characteristic ap- 

 pearances. 



Relation of Bacillus Alvei to Abnormal 

 Appearances. 



The most active and pernicious of the 

 comparatively large numbers of secondary 

 invaders in European foul brood is Bacillus 

 alvei. In the early days of the study of the 

 bacteriology of bee diseases it was thought 

 to be a pathogenic organism, as it was so 

 often found present in large numbers in the 

 dead larvae. This has since been proven not 

 to be the ease, for it is now known that 

 Bacillus alvei does not cause the death of 

 larvae. Bacillus alvei belongs to the group 

 of spore-forming bacteria, and practically 

 its only function, connected with European 

 foul brood carried out under the proper 

 conditions for its activity, is to decompose 

 the dead remains. As a result of this putre- 

 factive activity when present, changes in 

 the appearance of the remains occur to such 

 an extent as often to lead to much confu- 

 sion. This condition occurs most abundant- 

 ly where European foul brood is allowed to 

 run unchecked for some time and particu- 

 larly in regions where the disease is always 

 bad. 



In such cases as mentioned above it is 

 noticed that more and more of the larvae 

 seem to be affected shortly after being seal- 

 ed, at the time when they are still changing 

 position in the cells from coiled to extended. 

 Death generally occurs while they are still 



