iQiyj BOSAZZI—MTRlblCATIOX 207 



3. BouLLANGER, E., and Massol, L., Etudes sur les microbes nitrificateurs. 

 Ann. Inst. Past. 17:492-515. 1903. 



4. J0RD.4N, E. O., and Richards, Ellen H., Investigations upon nitrification 

 and the nitrifying organism. E.xperimental investigations by the State 

 Board of Health of Massachusetts, etc. Part II. Report on water supply 

 and sewerage. 188S-1890. pp. 865-881. 1890. 



5. Makrinoff, J., jMagnesia-Gipsplatten und IMagnesia-Platten mit organ- 

 ischer Substanz als sehr geeignetes festes Substrat fiir die Kultur der 

 Xitrifikationsorganismen. Centr. Bakt. II. 24:415-423. 1909. 



6. Omell-vnski, v., tjber die IsoHerung der Nitrifikationsmikroben aus dem 

 Erdboden. Centr. Bakt. II. 5:537-549. 1899. 



7. Perotti, R., Di una modificazione al metodo d'isolamento dei micro- 

 organismi della nitrificazione. Atti. R. Acad. Lincei V. 14:228-231. 1905. 



8. Stevens. F. L., and Temple. J. C, A convenient mode of preparing 

 silicate jelly. Centr. Bakt. II. 21:84-87. 1908. 



9. Wimmer, G., Beitrag zur Kenntniss der Nitrifikationsbakterien. Zeitsch. 

 Hyg. 48:135-174. 1904. 



10. WixoGR.^DSKY, S., Recherches sur les organismes de la nitrification. Ann. 

 Inst. Past. 5:92-100. 1891. 



11. , Recherches sur les organismes de la nitrification. Ann. Inst. 



Past. 5:577-616. 1891. 



12. , Contribution a la morphologie de la nitrification. Arch. Sci. 



Biol. St. Petersburg 1:87-137. 1892. 



13. , Die Nitrifikation. Handbuch der Technischen Mykologie. 



3:132-181 . 1006. 



EXPLANATION OF PLATE XIV 



The photomicrographs were made with the kind assistance of Mr. Victor 

 Dye, photographer of the Station. 



Fig. I. — Portion of sUica jelly i)late, showing colonies of Nilrosococais 

 after several additions of ammonium sulphate; solubilization of magnesium 

 carbonate in vicinity of colonies very evident; X i . 5. 



Fig. 2. — Colony of Nitrosococcus on sQica jelly plate, showing loosely 

 granular structure, as seen against a source of light; X77. 



Fig. 3. — Another colony on silica jelly; X 175. 



Fig. 4.— Nitrosococcus from culture undergoing intensive nitrification, 

 showing lack of zooglea formation; stained by malachite-green-gentian- 

 violet method of Winogradsky ; X820. 



Fig. 5. — Nitrosococcus from culture undergoing intensive nitrification, 

 showing small y9 forms imbedded in thick gelatinous membrane; cocci and 

 diplococci; stained by malachite-green-gentian-violet method of Wino- 

 gr.\dsky; X820. 



Fig. 6. — Nitrosococcus from culture undergoing intensive nitrification, 

 showing typical megalococci; in some cases the small forms are seen appear- 

 ing in thick gelatinous membrane, stained by malachite-green-gentian-violet 

 method of Winogradsky; X 1600. 



Fig. 7. — Nitrosococcus in hanging drop preparation, stained with Meiss- 

 ner's solution; X740. 



Fig. 8. — Nitrosococcus, same as no. 7 ; X 1 200. 



