6 



BULLETIN 431, U. S. DEPARTMENT OF AGRICULTURE. 



As sacbrood has been proved, however, to be a distinct disease and 

 different from all other disorders, naturally it is incorrect to use the 

 terms " sacbrood" and " pickled brood" synonymously, either in the 

 popular or in the technical sense. 1 



APPEARANCE OF HEALTHY BROOD AT THE AGE AT WHICH IT DIES OF 



SACBROOD. 





By comparing the appearance of healthy brood with that of brood - 

 dead of a disease, both the description and the recognition of the 

 symptoms of the disease are often materially aided. Before discuss- 

 ing the symptoms of sacbrood, therefore, a description of the healthy 



brood at the age at which it dies of sac- 

 brood will be given . In this description 

 the same method will be used and simi- 

 lar terms employed as will be found in 

 the description of the symptoms of the 

 disease. 



It will be recalled by those who are 

 at all familiar with healthy comb in 

 which brood is being reared that the 

 brood is arranged in such a way that 

 capped and uncapped areas occur alter- 

 nately and in more or less semicircular 

 fashion. Practically all cells in the un- 

 capped areas will be without caps while 

 practically all in the capped areas will 

 be capped. 



Since the brood that dies of sac- 

 brood, with but few exceptions, does 

 so in capped cells, a description of such brood involves the form, size, 

 and position of these cells. 



A cell (figs. 1 and 2) may be described as having six side walls, a 

 bottom or base, and a cap. (The cap has been removed by the bees from | 

 the cells from which these figures were drawn.) In general the six side 

 walls are rectangular and equal. These walls form six equal obtuse 

 angles within the cell (fig. 1) . The angle which is uppermost in the cell 

 (A x ) is formed by two sides which together may be termed the roof of 

 the cell. The angle which is lowermost (figs. 1 and 2, A 2 ) is formed by 

 two sides which with equal propriety may together be termed the 

 floor of the cell (fig. 2, F). When a cell is cut along its long axis 



1 For the purpose of an explanation for those who may have learned to refer to sacbrood. by the term 

 "pickled brood," it might be felt advisable by some to continue for a while in some way a reference to the 

 latter term. In such an event, the expression '-'so-called pickled brood "is suggested as being more nearly 

 accurate than the term "pickled brood." 



Fig. 1.— Looking into an empty worker cell 

 uncapped by bees. The uppermost angle 

 (AJjthe lowermost angle (A 2 ), the lateral 

 wall (L), and the wrinkling of the inner sur- 

 face of the cell near the opening, indicating 

 the presence of a mass of cocoons (C), are 

 shown. Enlarged about 8 diameters. 

 (Original.) 



