64 PHYSIOLOGICAL PROCESSES IN PLANTS 



4. Test for other food substances. Results ? 



Conclusion. Is most of the food matter of corn grains inside or outside 

 the embryo ? What foods are present ? 



Observations. 1. Use a hand lens. Note that the embryo lies in such 

 shape that the hypocotyl points toward the end that was attached, while 

 the plumule points the other way. 



Note. The tiny plumule is attached to that part of the embryo near- 

 est the pointed end of the corn grains, which has a single cotyledon. 

 Plants having but one cotyledon, as the corn, are known as monocotyle- 

 dons. 



2. Sketch a section as cut above x 3. Label all parts studied. 



Observation. Remove the endosperm from some corn seedlings that 

 have just germinated. Place on netting over water in a cup so that 

 the roots reach the water. Place with them an equal number of corn 

 seedlings with the endosperm present. Observe them for a number of 

 days. Results ? 



Conclusion. What is the use of the endosperm of corn ? 



PROBLEM XIII (Optional) 



A study of so7ne methods of plant breeding. 



a. Seed Selection 



Observations. 1. In 1892 about 880 varieties of apples were on sale 

 by American nurserymen. These were the result of seedlings coining up 

 here and there by accident. If so many were produced haphazard, do 

 you think better results might be obtained by careful selection ? 



2. Sort over a number of bean seeds of any one variety. Examine 

 numbers of ears of corn. Are they all exactly alike? If not, how do 

 they differ ? 



3. Select the seeds you think would produce the better plants. Notice 

 weight, color, size, shape, and number of kernels to the ear. 



Conclusion. Do you think it wise to carefully select seeds? Give 

 reasons for your selection in 3. 



Note. It is not sufficient to alone select what appear to be the best 

 ears, but we must know which can transmit their good qualities in the 

 highest degree, or find what is known as the " hereditary percentage." 

 Before this is done, the sprouting ability of the seeds should be tested, as 

 follows : 



