\. 

 The Intake of Carbon 217 



which has been expressed 1 g m~ h. This gram of sugar 

 involves the use of the carbon dioxid contained in 2.5 

 cubic meters. At the height of the growing season we 

 may count an average maximum of ten hours of work per 

 day; therefore, a grape-vine of the dimensions indicated 

 has the capacity of 10 X 10 = 100 grams per day, equiva- 

 lent to about 400 grams (about 14 oz.) of fresh substance. 

 To do this all the carbon dioxid would be taken from 250 

 cubic meters of air. 



Looking at this from the standpoint of a crop per acre, 

 an impressive though hazy picture may be had of the at- 

 mospheric changes concerned in the making of organic 

 material. A yield of 300 bushels of potatoes on an acre 

 involves, including tops and roots, about 5400 pounds of 

 water-free substance. Estimating as for making fruit 

 sugar (2.5 cu. m. or 3.2 cu. yd. per gram) there would be 

 required all the CO 2 to a height of more than one and one 

 third miles over this acre, assuming no gain meanwhile. 



LABORATORY WORK 



Chloroplasts. - - Study under the microscope the distribution 

 of the chloroplasts in one or more types of leaves available, such 

 as geranium, ivy, and tomato, using hand sections in all cases. 

 Contrast one of the above with the distribution in a species of 

 live-forever, purslane, or Begonia. In the best material study 

 carefully under high power of the microscope the forms of the 

 chlorophyll bodies and their cytological relations. In the young 

 leaves of moss, Elodea, or other convenient material determine 

 how multiplication of these bodies occurs. Study the form of 

 the chlorophyll in desmids, procurable either from an aquarium 

 or any pond containing algae. 



Light and the formation of chlorophyll. - - Germinate seed of 

 mustard, radish, or small grain upon moss or in small germi- 



