AMERICAN FOULBROOD. 7 



It is possible to recognize most cases of American foulbrood from 

 the general symptoms that are present. On the other hand many 

 cases can be diagnosed only by an exact knowledge of the postmortem 

 conditions of brood dead of the disease. A close study of these 

 appearances, therefore, is advisable. The following somewhat brief 

 description of larvae and pupae dead of the disease will suffice in 

 most instances and will serve as a guide to further observations. 



SYMPTOMS MANIFESTED BY THE BROOD 



Signs that will determine the exact time of death from American 

 foulbrood have not yet been ascertained. As the larvse and pupae 

 that die of the disease do so at a period in their growth when healthy 

 brood is motionless, lack of motion is no guide. In the descriptions 

 made in the present paper it is assumed that a larva or pupa is dead 

 if it shows a change from a bluish-white, more or less transparent 

 appearance to one that is more nearly white, more nearly opaque, 

 and shows at the same time a change from the normal turgidity to 

 a slightly flaccid condition. 



The appearance of the larval and pupal remains changes gradually 

 from day to day from that of a healthy brood to that of the dried 

 residue — the scale. A description, therefore, that would be correct 

 for one day would be incorrect probably for the following day. 

 Furthermore, all of these remains do not pass through the same 

 changes. For convenience in description, therefore, the various 

 appearances assumed by them are considered in five more or less 

 arbitrary stages. The interpretation of the descriptions will be 

 aided if the description of healthy brood (p. 3) is borne in mind, 

 since the terms used are similar in both instances. 



LARVAE DEAD OF AMERICAN FOULBROOD 



The descriptions made of dead larvae (prepupae) for the most 

 part will be of those that have died during the 2-day quiescent 

 period just preceding the transformation to the pupa, as most larvae 

 dying of the disease succumb at this age. 



FIRST STAGE 



The first symptoms of American foulbrood appear about the end 

 of the first week after infection. From the bluish white of the 

 healthy larva the color changes during this first stage of the disease 

 to a very light brown. The conelike anterior third (PI. II, E) having 

 settled somewhat, the apex is now slightly farther from the roof. 

 The surface markings in each of the three thirds (PI. II, H) are very 

 similar to those of a healthy larva. The body wall is easily ruptured, 

 but by care the larva may still be removed intact from the cell. In 

 consistency the decaying tissues are soft and nonviscid. 



