52 Proceedings of Indiana Academy of Science 



activity of the green plant is therefore easily realized. Recently studies 

 have been made concerning carbohydrate substances of Thallophytes, 

 Bryophytes and leaves of Angiosperms and methods for their estima- 

 tion in the extracts (86). The amount of chlorophyll is really very 

 small per unit area and Tschirch has estimated that only 0.1 to 0.2 

 gram is usually present per square meter of green leaf surface. Much 

 work remains to be done on chlorophyll activities with various autotrophic 

 plants of different colors and under different conditions of light composi- 

 tion. Marine plants suffer from light conditions as the water deepens 

 and at a depth of 400 meters in the sea autotrophic plants cease to 

 exist (1, Bd. I, p. 337). The chloroplasts of some plants can continue 

 to live and carry on the process of photosynthesis for a short time 

 when removed from the cell (87), but all attempts to grow them outside 

 of the cell permanently have failed. The chlorophyll of green plants 

 breaks down in solution. Wahmsley (88) states that he has preserved 

 a specimen of Draparnaldia in camphor water for 20 years and that the 

 chlorophyll remains unchanged. This, however, says nothing as to the 

 actual preservation of the chlorophyll itself. Concerning those sub- 

 stances which form the chlorophyll only a faint intimation exists which 

 creates a wide field for study. 



A large field for investigation i.-^ brought out by Fitting in his 

 interesting paper on a new branch of physiology which he names 

 "Geographical Physiology" (89). The various theories concerning carbon 

 dioxide assimilation have been well summarized by Schroeder (90). 

 One which is much quoted may be mentioned, namely Bayer's Theory 

 "according to which formic aldehyde is produced from carbon dioxide 

 and water in the chloroplast, oxygen being evolved, and carbohydrates 

 resulting by polymerization" (1, Bd. I, p. 340). Doubt attaches to 

 this theory. More recently Ewart states "that not formaldehyde but 

 a biose sugai- is the first pi'oduct in photosynthesis and the traces of 

 formaldehyde which have been detected in green plants are the result 

 of the destructive photo-oxidation of chlorophyll and are formed equally 

 well in the entire absence of carbon dioxide when extracted chlorophyll 

 is exposed to light" (91). Attention is also directed to the (juestion 

 of photosynthesis and the Electronic Theory (92). 



Professor Giacomo Ciamician of Bologna, Italy, made an interesting 

 address some years ago in New York which has a bearing in this con- 

 nection. He asked "why use only the fossil energy of the sun — for that 

 is what we do when we burn coal! Why should not man use sun power, 

 direct, as do plants and trees?" (93) According to one estimate he 

 made, the sun delivers in energy by means of its rays enough power in 

 six hours to equal 2, .500 tons of coal per square mile. We mine in the 

 U. S. about 600,000,000 tons of coal per year while the Sahara Desert 

 receives daily in .'^olar energy the equivalent of 6,000,000,000 tons of 

 coal every day. He indicated by a long list of chemical processes the 

 probability of the consummation of his ideas and prophesied a trend 

 toward the tropics which would on this account become thickly populated 

 in time. Slosson says "man takes a 1,000 horse power engine and an 

 electric furnace at a temperature of several thousand degrees to get 



