BY R. GRBIG-SMITH. 89 



EXPLAN'ATiON OF PLATE IX. 



Colonies growing on the surface of Nutrient Agar. 



1.— Cobny of Al. 



2. — Colonies of Al and A2a growing side by side. The almost homogeneous 



character of Al and the cog-wheel structure of A2a are brought out. 

 3. — Colony of A2. This was a specially translucent colony. They are generally 



opaque, except at the margm. 

 4,- — Colonies of B2. Thickly sown colonies, showing the ivy-leaf structure. 

 5. — Colony of B2. Mature colony, showing the r.nesenteric structure. 

 6. — Ropy Bark infusion, flowing siphon-wise. 



(Photographed by Mr. W. W. L'Estrange.) 



