24 



XXXVIII. Some Underground Growths. 



Collect typical samples of potato tuber, carrot, turnip, and mang-el or 

 beet, — 



1. Examine the arrangement of the "eyes" on a large potato tuber, 

 and note where they are most numerous. 



2. Cut longitudinal and cross sections passing through an "eye." 

 Make drawing, and determine the nature of an " eye." How many 



buds in an " eye "? 



3. What reasons have you for supposing the tuber to be a modified 

 stem ? Illustrate by drawings. Locate the cortex, epidermis (peri- 

 derm), vascular cylinder, cambium ring, and pith. Where is the wood? 



4. What is the chief reserve food stored in the tuber ? How would 

 you test its presence ? 



6. Do the true roots rise above or below the tuber-bearing branches 

 in field ? 



6. What is the advantage of exposing the tubers for planting to 

 light for a week or more ? 



7. What is generally the shape of the carrot? How are the small 

 secondary roots arranged ? 



8. Make longitudinal and cross sections of a carrot ? Note color, 

 thickness, and texture of the various parts. Draw. 



9. Has a carrot a root or a stem structure ? Where is the base and 

 the cortex ? the wood ? the cambium-ring ? 



10. What is the difference between (1) the root of cultivated and wild 

 forms of carrot, and (2) the first and second year's growth ? 



11. Make longitudinal and transverse sections of a turnip. Draw. 

 No.te color, thickness, and texture of the various parts. 



12. Locate bast, cambium and wood. Of what is the wood com- 

 posed ? 



13. Make longitudinal and transverse sections of a mangel or beet. 

 Draw; note color, thickness, and texture of the various tissues and soft 

 parenchyma. Which parts are colored ? Name the parts as seen in 

 sections. 



[Consult Percival's Agricultural Botany.] 



XXXIX. Spiders. 



Field excursions should be made for the study of the work and habits 

 of spiders. A few spiders may be brought into the class-room and placed 

 in the terrarium, where their habits can often be readily observed. 



1. Find orh-^vehs, funnel-wehs, coh-wehs, and the threads of the 

 balloon spiders. Make drawings of the structure of each web, and note 

 where each web is found. 



