J 5 



there were anything in air beside CO2 that helped in photosyn- 

 thesis the plant would be sure to have it. Tube B is kept closed 

 except when it seems necessary to introduce water through it to 

 the plant. Before commencing the experiment the leaves of the 

 plant were found to contain starch, but after continuing it three 

 days all traces of starch disappeared, thus proving that COj is 

 necessary in photosynthesis. 



" The department editor * wishes to raise four questions relative 

 to this experiment : 



1. Do the pupils know enough chemistry to enable them to 

 prove that NaOH or Ca(0H)2 takes COg from the air ? 



2. Is it true that forcing the air through the liquid in the 

 cylinder by means of tube A, and out of the bell jar through tube 

 B " for a few minutes " would render " most of the air in the bell 

 jar" devoid of COj? 



3. How does the pupil know that in watering the plant through 

 tube B you do not introduce COg sufficient for the plant's uses ? 



4. Does this prove " that CO2 is necessary in photosynthesis "? 

 " Do not all the points raised in these questions refer to things 



that the student must take for granted upon the authority of the 

 teacher? If so, would it be quite as well for the pupil to assume 

 in the beginning that the teacher is correct when he says that 

 CO2 is necessary to the process of photosynthesis ? " 



The Outlook of December 19 has a short, practical article on 

 forest fires and their prevention, written by Alfred L. Donaldson. 



The increasing interest taken in our national forests is indicated 

 by Speaker Cannon's statement that three years ago they cost 

 three hundred and seventy-five thousand dollars, this year, nearly 

 four million, and the estimates for next year are about six mil- 

 lion dollars. 



The North American Review for November, 1908, contains an 

 article by GifTord Pinchot on " The Foundations of Prosperity" 

 which is well worth reading, Mr. Pinchot remarks that the 



* Professor O. W. Caldwell, School of Education, University of Chicago. It is 

 with his permission that this article is reprinted from School Science and Mathematics. 

 — EDrroR's Note. 



