Apr. 3-sept. 25. i9j6 Illustrations 



XV 



The Disease op Potatoes Known as "Leak" 



Plate XC. Potatoes affected with potato leak: Fig. i, 2. — Natural infection 

 from fork woimd. Fig. 3. — Rot produced by inoculation with Pythium 

 debaryanum. Fig. 4. — Rot produced by inoculation with Rhizopus nigri- 

 cans 



Page 



640 



Some Properties of the Virus of the Mos.^ic Disease of Tobacco 



Plate XCI. Livingstone atmometer porus cup as used for filtration 674 



Life Cycles op the Bacteri.a 



Plate A. Fig. i. — Azotobacter 11. Mannite-nitrate solution, 5 days old. 

 Types A and La. Some cells in conjunction. Fig. 2. — Azotobacter 21. 

 Contact preparate from a colony on mannite agar, 4 days old. Types A, L. 

 Most cells in conjunction. Fig. 3. — Azotobacter 23. Contact preparate 

 from a colony on mannite-agar, 4 days old. Types A, B, I, Ka, and many 

 conjunct cells. Fig. 4. — Azotobacter 13. Jannite-nitrate solution, 17 days 

 old. Type KX. Fig. 5. — Azotobacter 14. Mannite-nitrate solution, 5 

 daysold. Type B forming I. Fig. 6. — AzotobacterS. Beef bouillon. Type 

 B forming types I and J '. 702 



Plate B. Fig. 7. — Azotobacter 21. Mannite-agar colony, 4 days old. TypeC 

 forming types D and I. Fig. 8. — Azotobacter 22. Mannite-agar colony, 

 4daysold. Type C forming D, also A in conjtmction. Fig. 9. — Azotobacter 

 II. From a filter paper strip in mannite-peptone solution, 16 days old. 

 Types A and B forming D. Fig. 10. — Azotobacter 3. Mannite-peptone 

 solution, 24 days old. Types L and M forming D. Fig. 11. — Azotobacter 

 II. Mannite-peptone solution, 16 days old. Type D (stained) resulting 

 from Type C. Fig. 12. — Azotobacter 6. From condensation water of 

 mannite-agar slant, i day old. Type D (vmstained) containing regenera- 

 tive units 702 



Plate C. Fig. 13. — Azotobacter 24. Mannite-nitrate solution kept 5 days after 

 having been heated i minute at 96° C. Types I and F developing from 

 D. Some I germinating in conjunct stage and inclining to form spores. 

 Fig. 14. — Azotobacter i. Mannite-nitrate solution, 10 days old. Types B, 

 K/3, E, and Fa developing from stained and unstained type D. Fig. 15. — 

 Azotobacter 15. From condensation water of a mannite-nitrate agar slant, 

 2 days old. Types Fa and F/3 developing from type D. Fig. 16. — Azoto- 

 bacter 17. Mannite-soil-extract agar, 2 months old. Type E, Fa, K^, and 

 G developing from type D. Fig. 17. — Azotobacter 17. Mannite-nitrate 

 agar, 10 days old. Preparate treated with hot aqueous fuchsin. Type G, 

 partially dissolved; also K^. Fig. 18. — Azotobacter 7. Mannite-soil- 

 extract solution, 14 days old. Type H forming D 702 



Plate D. Fig. 19. — Azotobacter 2. Mannite-nitrate agar, 23 daysold. Spores 

 formingtypeD. Fig. 20. — Azotobacter 2 . Mannite nitrate-agar, 6 daysold. 

 Types L and F, endospores and exospores and dissolving of spores to type 

 D. Fig. 21. — Azotobacter 18. From a filter paper strip in mannite solu- 

 tion, 25, days old. Type L with gonidia, forming B (type JX). Fig. 22. — 

 Azotobacter 7. Mannite-soil-extract agar, 2 months old. Types E and F 

 forming B. Fig. 23. — Azotobacter 7. Mannite-soil-extract agar, 2 months 

 old. Type B, formed by types E and F, germinating to type G. Fig. 24. — 



Azotobacter 7. Mannite-soil-extract agar, 2 months old. Type K7 702 



55854°— 16 2 



