1898.] NATURAL SCIENCES OF PHILADELPHIA. 119 



Fig. 6. — Degeneration of the coleopodia, from overproduction of 



gelatinous substance, resulting in adherence. Stained as 



before. 

 Fig. 7. — Degeneration of the whole coleoderm, which is infested 



with bactaria in colonies. Gentian violet. 

 Figs. 8 and 9. — Coleopodia under higher magnification, showing 



differential staining by Bismarck brown and eosin. 



Plate vii. 



Fig. 1. — Ventral girdle view of cleaned frustule of Eunotia major X 

 925. 



Fig. 2. — Optical section of the same frustule, showing the end raphe 

 and channels leading to raphe and pseudo-nodule, X 925. 



Fig. 3. — Dorsal girdle of the same frustule, X 925. 



Figs. 4 and 5. — Motile frustules of Eunotia major, stained with Bis- 

 marck brown and tannic acid, X 315. 



Fig. 6. — An enlargement of 4 (X 435). 



