46 BULLETIN" 809, U. S. DEPARTMENT OF AGRICULTURE. 



PLATE VI 



Various phases of the appearance of brood dead of American foulbrood: 



A.— Larva in cell not yet capped, dead of American foulbrood. 



B — A developing bee dead of American foulbrood immediately before entering the pupal stage. 



C. — A punctured cap with two holes. 



D. — Larva dead of American foulbrood gnawed and partially removed by the adult bees. 



E. — End view of larval scale. The cap was removed artificially. 



F.— End view of pupal scale. 



G. — Lateral view of healthy larva in capped cell. 



H.— Lateral view of larval scale in the cell cut lengthwise. The cap had been removed by the adult bees. 



I.— Lateral view of pupal scale in position in cell cut lengthwise. 



PLATE VII 



Vegetative form, spore formation, spores, flagella, and giant whips of Bacillus larvae. Photomicrographs: 



A.— Vegetative form from a 24-hour culture on the surface of brood-filtrate agar, x 1000. 



B.— Spore formation and spores from the surface of brood-filtrate agar. X 800. 



C— Flagella. Stained by Loeffler's method as modified by Johnson and Mack. X 1000. (Retouched.) 



D.— Spores from a stained smear made directly from a decaying larva dead of American foulbrood. X 

 1000. 



E.— The production within the rods of separate elements, each being supplied with flagella. X 1000. 



F. — Giant whips and small spherical bodies in the older cultures of B. larvae obtained from the water of 

 condensation of a brood-filtrate-agar slant culture. Fixed in 50 per cent formalin and stained with carbol 

 fuchsim X 1000. 



G — Small and larger giant whips, and spherical bodies similar to those of F. X 1000. 



A similarity existing between the microscopic appearance of giant whips and spirochetes caused Maassen 

 (14) to believe them to be spirochetes and to introduce the name Spirochaeta apis. 



H.— Very large whip, and spherical bodies similar to those of F and G. X 1000. 



PLATE VIII 



Colonies and cultures of Bacillus larvae: 



A.— Surface colony and deep colonies as seen in brood-filtrate agar plates. 

 B.— Surface colony on brood-filtrate agar more highly magnified. 

 C. — Deep colony in the same medium, magnified. 

 D — Surface growth on brood-filtrate-agar slant. 



E.— Culture of Bacillus larvae in bee-larvse agar when the Liborius method is used. The growth is 

 throughout the upper third of the medium. 

 F.— The culture is similar to E but the growth is nearer the surface. 



G. — The culture is restricted in the agar and is near to but not at the surface of the medium. 

 H.— The growth is less restricted in area and farther from the surface than in G. 

 I.— The growth is very restricted in area and is below the middle of the medium. 



O 



