40 TECHNICAL BULLETIN 14 9, XT. S. DEPT. OF AGEICtTLTURE 



the presence of mycelium within the tissues. Diagnosis may also be 

 made from the post-mortem changes. 



The action of pathogenic fungi upon the tissues of bees is both 

 physical and chemical in nature. Tissues are penetrated by the de- 

 veloping mycelium and are digested by the fungous enzymes. One 

 pathogenic fungus, Aspergillus ftavus Ao5c, was shown to produce 

 a transient toxic substance which is the cause of fatal poisoning in 

 bees. 



None of the species of Penicillium encountered attack healthy bees 

 in nature. Mucor hieTnalis attacks bees under proper conditions, but 

 several other species of Mucor studied appear to be harmless. 



Yeasts were found to be more or less constantly present in the 

 alimentary canal of bees, although, except in extreme cases, bees are 

 normally unaffected by their presence. A number of yeasts, how- 

 ever, including Sac char omxyces eUipsoideus, S. cerevisiae, S. apicu- 

 latus, Mycode'nna cerevisiae, and baker's yeast, are pathogenic when 

 introduced into the blood of bees. Yeasts rarely if ever gain entrance 

 to the blood of healthy bees in nature ; conseqttently they appear to 

 be of little significance pathogenically. 



Filamentous fungi, differing from those investigated, have also 

 been observed vegetating in tissues of sick bees, but inoculations 

 have uniformly given negative results. 



The observations made thus far tend to indicate that bees become 

 infected from beekeeping equipment, dead bees, and molded combs, 

 and from molded fruit and other substances that contain a high con- 

 centration of sugar. 



Badly molded combs and equipment within the hives of infected 

 colonies should be disinfected by being dipped or washed in a 20 

 per cent solution of formalin in water or by being exposed to 

 formaldehyde gas. 



LITERATURE CITED 



(1) Ai-SBERG, C. L., and Black. O. F. 



1913. CONTSIBUTIONS TO THE STUDT OP MAIZE DETEEIORATION. BIOCHEMI- 

 CAL AND TOXICOLOGICAL INVESTIGATIONS OP PENICIIUUM PUBEBIJ- 

 LUM AND PENICILLIUM STOLONIFEEUM. U. S. Dept. Agr , Bur. 



Plant Indus. BuL 270, 48 p., illus. 



(2) Bahr, L. 



1916. DIB KRANKHEITEN DEB HONIGBIBNEUNDIHBEB BRUT. DeUt. Tierarztl. 



Wclmselir. 24 : 255-258, 264-266, iUus. 



(3) Blakbsleb, a. F., and Goetnee, R. A. 



1915. REACTION OP RABBITS TO INTRAVENOUS INJECTIONS OF MOULD SPOEES. 



Biochem. Bui. 4 : 45-51, illus. 



(4) BUCHNEE, E. 



1903. DIE ZTMASEGARUNG UNTEESUCHUNGEN UBBE DEN INHALT DEE HEFEZBL- 

 LEN UND DIB BIOLOGISCHB SEITB DBS GAEUNGSPEOBLEMS. I. TEIL : 



XTBEB. DIE ZTMASEGAEUNG. 286 p., Ulus. Munchen and Berlin. 



(5) BUBNSIDE, C. E. 



1927. SAPROPHYTIC PUNGI ASSOCIATED ViriTH THE HONEY BEE. Mich. Acad. 



Sci., Arts, and Letters, Papers 8 : 59-86, illus. 



(6) Claek, W. M. 



1922. the determination op hydrogen ions. an elementabt treatise 

 on the hydrogbh^ e2-ectrode, indicator and supplemia^tary 

 methods with ax indexed bibliography on applications. ed. 

 2, 480 p., illus. Baltimore, 



