1886.] NATURAL SCIENCES OF PHILADELPHIA. 341 



EXPLANATION" OF PLATE IIL 



The drawings were made with a camera lucida and a Spencer's y'o-objec- 

 tive, homogeneous immersion, of 125 balsam angle. They are unifoimly 

 magnified 890 diameters. 



Fig. 1. Micrococcus amylovorus Bur., grown upon a slice of boiled 



potato, stained with Bismarck-brown and mounted in Canada balsam. 

 Fig. 2. From a cultivation in hay infusion : a, separate bacteria ; 6, zoo- 



gloea. The large mass, only part of which is shown, is made up of 



smaller masses more or less united. 

 Fig. 3. Small zoogloea from a potato infusion, drawn from a preparation 



in Canada balsam, stained with Bismarck-brown. 

 Fig. 4. Poition of a zooglcea mass from the same culture, showing an 



envelope free from bacteria. Drawn from an unstained preparation 



mounted in glycerine. 

 Fig. 5. Three zoogloea from the same culture. 

 Fig. 6. From another culture in hay infusion. 



