FOR WAGGONER'S BIOLOGY 
35 
EXERCISE 38 (Supplementary) 
OAT SMUT 
Use specimens collected during the summer. (Obtain these 
when the oats are heading.) 
I. Examine oat plants which are affected by oat smut. Where 
is the smut found? When does it appear? What part of the plant 
is affected by it? In what way does it injure the plant? How is 
oat smut spread? Why is the prevention of a recurrence of this 
smut a comparatively simple matter? (See Waggoner, Page 189 
and Fig. 117.) 
II. Study some of the spores which have been mounted under 
the microscope. Note their size, color, and shape. Draw several 
spores. Draw a spikelet of the infected oats. 
EXERCISE 39 (Supplementary) 
POTATO SCAB 
The pupils may bring specimens which show this disease. 
I. Examine a potato tuber which is affected by the scab. What 
injury does this scab do to the potato? Cut sections through the 
potato. How deep are the diseased spots? Is the interior affected? 
Is there any evidence that other organisms may have had a part in 
the resulting injuries? Do you find spores? How is the disease 
transmitted and how can this transmission be prevented? (See 
Waggoner, Page 191.) 
II. Draw an exterior view of a scabby potato and also a section 
of a potato showing the nature of the scab injury in the interior. 
EXERCISE 40 
YEAST — STRUCTURE AND REPRODUCTION 
I. Place a cake of dry yeast in water and allow to stand over 
night. Study the resulting mixture. Note the odor and appear- 
