February, '16] MCCRAY: BROOD DISEASE DIAGNOSIS 193 



over, a very similar odor may be present in other conditions, probably 

 in brood which has died from almost any cause, barring American 

 foulbrood and sacbrood. The odor in American foulbrood may be 

 very feeble, or absent altogether, and probably sometimes disappears 

 on exposure to the air outside of the hive. Infected brood in the comb 

 will undoubtedly absorb other odors if given the opportunity, thus 

 the original characteristic odor of American foulbrood may be masked. 

 This has been observed where specimens of comb and diseased brood 

 from various sources have been thrown together in the waste basket 

 and carted to the basement and allowed to lie there for some time pre- 

 paratory to being destroyed. No odor has been detected in sac- 

 brood. Odor is of value, therefore, only in American foulbrood. Color 

 is usually regarded as of considerable value in differentiating between 

 American foulbrood and European foulbrood. This is true in many 

 cases but coloration is not by any means constant for either disease. 

 Thus the coloration in some cases of American foulbrood, where young 

 larva3 are affected, may closely resemble the usual coloration of most 

 cases of European foulbrood. This usually leads to the mistake of 

 diagnosing American foulbrood as European foulbrood or to that of 

 diagnosing the presence of both diseases in the same comb. The con- 

 sistency of the broken down larval mass is one of the most constant 

 factors, yet this may not be sufficiently pronounced, as for instance the 

 ropiness in American foulbrood, to differentiate as between it and 

 European foulbrood. Especialty confusing are those cases where in 

 addition to the lack of ropiness there is present, as just mentioned in 

 some cases of American foulbrood, coloration closely resembling 

 European foulbrood. The age of the infected larvae is usually an im- 

 portant aid in diagnosing between American foulbrood and European 

 foulbrood. Every beekeeper, who knows anything about disease at 

 all, has learned that in American foulbrood it is the older larvae as 

 a rule, or even pupse, that present the manifestations of disease, 

 while in European foulbrood diseased larvae, much younger than in 

 most cases of American foulbrood, are found. If not infrequently hap- 

 pens that the germs of American foulbrood give evidence of their pres- 

 ence in the larvae at about the age at which European foulbrood usually 

 manifests itself and, to increase the difficulties of differentiating, again 

 the coloration of the larvae and the general appearance may very 

 closely simulate European foulbrood. To illustrate some of the 

 variations just enumerated, I wish to describe for you the following 

 specimen of diseased brood : Specimen No. 4725 from the apiary of 

 John Kessler, Watertown, Jefferson County, Wisconsin, sent by Mr. 

 L. V. France and examined by the writer July 1, 1915. The sample, 

 it was stated, was obtained June 29, 1915, hence was examined pre- 



