Apr. 12, 1924 Development of American Foulirood 133 



death of the larva in the intestinal tract and usually kills before sealing takes 

 place, as differentiated from American foulbrood as described above. Unfor- 

 tunately, as yet it has been impossible to grow this organism in pure culture on 

 artificial culture media. 



Further work has been done by various investigators on certain laboratory 

 phases of the bacteriology and diagnosis of the two diseases, but no additional 

 information has been obtained concerning the etiological and biochemical rela- 

 tionships of the causative organisms which would aid fti the solution of the 

 present problem. 



BASIS FOR INVESTIGATIONS 



Throughout all the discussion of symptoms of the brood diseases in the litera- 

 ture, particularly in relation to the different ages at which the diseases attack 

 during the life history of the larvse, there has been no adequate explanation of 

 the reason for this apparent fundamental difference. 



Maassen (2S) in the case of American foulbrood made the observation that, 

 "according to the microscopic findings from section preparations. Bacillus 

 brandenburgiensis [Bacillus larvae] does not come to luxuriant development in 

 the intestine of the larva, though this is the case with Bacillus alvei and with 

 Streptococcus apis [in 'sourbrood']. It finds much more promising nourishment 

 in the fat bodies of the larva. Apparently the bacillus finds opportunity to press 

 its way into the fat bodies shortly before the pupation of the bee, at the begin- 

 ning of the natural changes in the intestinal tube. From this it seems clear 

 why the larvae containing Bacillus brandenburgiensis die after sealing." In part 

 this is probably correct, since it may easily be observed that soon after capping the 

 tissues of the healthy larva become more or less granular and watery in consistency , 

 at which time it is almost impossible to distinguish the intestinal tract. It is also 

 difficult to remove the larva in this condition from the cell without rupturing the 

 skin envelope. This process is described more in detail later. It does not 

 explain, however, why the spores of Bacillus larvae do not germinate and increase 

 in numbers suflBciently to kill the larva much earlier during the feeding period, 

 as in the case of European foulbrood. A vague and only partially correct sug- 

 gestion was given in an earlier paper by the writer {4S), in which the following 

 theory was stated: "Bacillus larvae gains entrance to the larva generally in the 

 spore stage, in the larval food. This occurs at about the same stage as in Euro- 

 pean foulbrood, while the larva is still coiled in the cell. Only rarely, however, 

 do coiled larvae die. This is apparently because it takes some time for the rest- 

 ing stage spores to germinate into the active vegetative rods. This causes death, 

 as a rule, to occur later in the life history of the larva." 



KEIATION OF THE BROOD DISEASES TO THE LIFE HISTORY OF THE 



HONEYBEE LARVA 



The development of the honeybee may be divided in general as follows: After 

 the egg is laid there is a period of three day's incubation before it hatches into 

 the larva. The larval stage, during which active feeding and growth occur, 

 comprises four and a half to five and a half or six days. At the end of the feeding 

 period the larva is sealed in the cell, where it spins its cocoon. Metamorphosis 

 then occurs, and the fully formed adult bee emerges in about 12 days, making a 

 complete developmental period of approximately 21 days. According to White 

 (63) , there is a prepupal period in healthy brood of four days after sealing occurs 

 before the actual change in the external form to that of the adult bee takes place. 

 During the first t^o days after capping, the larva is active in the cell, consuming 

 any remaining food and spinning a cocoon. Some time during this period ac- 

 cording to Straus (^S), or just previous to capping according to Zander (57) 



