222 THE TEACHING BOTANIST 



Your record should show the exact relation be- 

 tween the gross and the cellular anatomy. 



44. What is the cellular anatomy of the Aristolochia 



stem ? 

 Answer as in the preceding. 



45. Construct two diagrams showing by colors the 



homologies of the tissues in the two stems. 



46. With the Aristolochia stem compare a piece 



of Oak wood. What are the homologous 

 parts ? 



47. The phenomena accompanying growth in size, 



and how it is affected by external conditions, 

 are best manifest in stems. To study it properly 

 we must provide some method of measuring 

 its amount, and preferably some method that 

 will be self-recording. This is accomplished 

 by the auxanometer used in Experiment 8. 



Under ordinary conditions, at what time in the 

 twenty-four hours does an ordinary plant grow 

 most in length ? Answer by Experiment 8. 



In what way does temperature affect rate of 

 growth ? 



Materials. Indian Corn stems under i cm. diameter, put 

 in formaline in summer, are needed. Aristolochia sipho, the 

 " Dutchman's Pipe," grows over porches in most towns, and 

 is the classic stem for the purpose, showing with the greatest 

 clearness, in comparison with the Corn, the relation between the 

 exogenous and endogenous composition of the stem. 



