126 A NEW BACILLUS PATHOGENIC TO FISH, 



may break up into noccules which slowly gravitate, leaving the 

 upper liquefied gelatine clear, the lower layers turbid. The 

 appearances are never like 36, i. or 36, ii., but approach 38, iv. 

 ( Lehman n and Neumann, Diagnostik, i.). These appearances are 

 similar with 15 and 20% nutrient gelatine. 



Glucose-gelatine shake — There is no gas developed. 



Agar plate. — The colonies are white and may assume various 

 shapes. The surface colonies may be rounded with an irregularly 

 lobed margin and a white central point where the surface growth 

 has originated from a subsurface colony, or when the growth has 

 always been upon the surface the centre may be dark. In cases 

 where the agar surface is moist, the colony may send out amoeboid 

 processes which gradually extend over the whole surface after the 

 manner of Bad. vulyare. The colonies just below the surface 

 may send out processes into the agar medium. The organisms 

 may also grow as a film between the solidified agar and the glass 

 of the Petri dish. When examined with a 60-fold magnification 

 the colonies are seen to be highly granular. The margins of the 

 surface colonies are sinuous or waved, and are seen to consist of 

 filaments The subsurface colonies are irregular in outline and 

 beset with fibrous projections. The processes sent out by the 

 subsurface colonies into the agar medium are seen to be composed 

 of interlacing filaments. 



Agar slope. — A matt, white expansion is quickly formed. It 

 is slightly raised, and has an irregular margin which, when viewed 

 with a lens, appears bristly. The expansion becomes folded or 

 wrinkled, and approaches that figured in 38, viii. (Lehmann and 

 Neumann). When touched with the needle the growth, when 

 the medium is moist, breaks into crystal-like masses, or adheres, 

 when the medium is dry, as a tough skin. When spore formation 

 has set in, the growth becomes glistening, the folds or ridges 

 become flatter, and when touched at this stage with the needle 

 the consistency is found to be that of butter. 



Agar stab. — The needle track develops an uncharacteristic 

 filiform growth. The white surface growth spreads and becomes 

 wrinkled or corrugated as 38, viii. (Lehmann and Neumann). 



