1890-91.] PEACH YELLOWS. 215 



Bacilhis A — Found in 21 per cent, (about) of the affected trees: 

 Under the microscope — small bacillus, even staining, frequently in pairs, 

 rounded ends, and very often curved. Size, 5 to 6/^X9/^-. Stains well 

 with Mythyl. Blue (Alk.), Fuchsin (carbolic), and by Gram's method. 



Hanging Drop. — Very active. 



Cnlture. — Appeared on surface of agar-agar two days after inoculation 

 as a small, white, thin, moist colony. 



Agar-agar plate. — Small white col. which under low power is yellowish 

 white, irregularly round colony with irregular wavy edge and dark 

 central spot, flat and finely granular ; slightly dome shaped thinning 

 away at the edge to transparency. 



Agar-agar stab. — White healthy growth spreading well on the surface 

 of agar-agar as smooth, white, glistening colony, not moist. It grows 

 well along the needle track, not tapering at all, but same thickness 

 throughout. 



Gelatine plate. — Small, round, white col. which is about Y^ m.m. in 

 diameter at the end of five days. Under low power of microscope the 

 surface colonies look like perfectly round, smooth, yellowish white 

 colonies, flat surface, semi-transparent, edges thin and very smooth. 

 (The very thin colonies show fine granulations.) Some colonies seem to 

 be made up of rings of different depths of color ; no liquefaction at 

 end of three days but commencing on the fifth and proceeding rapidly. 



Gelatine stab. — Grows rapidly and well in gelatine. No liquefaction 

 at end of six days. Appears as yellowish white, smooth, moist look- 

 ing colony, spreading on the surface with an irregular outline ; grows 

 slightly along the track of the needle as a very finely granular growth, 

 tapering from the surface and not spreading in the gelatine. After 15 

 days liquefaction commencing and proceeding in a champagne-glass form. 

 The surface is covered with the tenacious, slimy colony and the liquefied 

 gelatine is cloudy with fine granules with a precipitate of the same nature. 

 Rest of the medium clear. After about 20 days the liquefaction has 

 extended over|the whole surface of gelatine, and it is gradually all becom- 

 ing liquefied with the above characters continued. 



Bonillon. — Produces fine white growth on surface which sinks on a 

 gentle shaking of the tube. The whole of the medium becomes misty 

 in appearance, due to fine white granules suspended throughout the 

 Bouillon. 



Potato. — Yellowish white, elevated, convex growth with smooth, dry 

 surface, extending very slightly beyond the line of inoculation. Surface 



