43 
10. When dry, fix the preparation made from the crushed nodule, and stain 
in dilute (1:5) fuchsin for three minutes. 
11. Examine, draw and describe the plant on the desk. Leave the roots in 
the water for this purpose. Carefully examine the nodules. Note their shape, 
color, position, and size. 
12. Examine the stained preparation made from the nodule. Look very 
carefully for irregular shaped cells: pear, club, Y and T-shaped individuals. 
It is quite possible that all of these shapes may not be seen in the same prepa¬ 
ration. The bacteria when appearing in these shapes are called baderoids. 
Draw and describe the organisms. See instructor’s demonstration. 
13. Draw and describe typical nodules from the preserved specimens of red 
clover, alfalfa, soybeans, garden peas, and lupine. 
14. Prepare a sjide from one of the colonies marked by the instructor and 
examine the organisms as before. 
(a) Are there any bacteroids? 
( b ) What kind of organisms are present? 
15. Examine the pure cultures of Rhizobium radicicolum furnished. Draw 
and describe the culture according to the outline of the study of cultures. 
16. Examine the organisms after staining them with crystal violet or carbol 
fuchsin. Be sure that some of the gelatinous growth is on the slide. The 
organisms will appear unstained on a stained background. 
17. Draw and describe the organisms as seen with the oil-immersion 
objective. 
18. 
(a) What was the shape of the organisms as seen in the nodule? 
As seen from the colony? As seen from the streak culture? 
( b) What type of structure was revealed in the organisms from 
the nodules? 
(c) What are bacteroids? 
( d ) What is the difference between the organisms in the nodules 
and those in the pure cultures? 
(e) What relation do these organisms bear to the nitrogen supply 
of legumes? 
(0 Why are legumes such good crops for the land? 
(g) What is meant by inoculation of legumes? 
(/?) When is inoculation necessary? 
