PART SEVEN 



PHYSIOLOGY 



Physiology deals with the functions of plants such as res- 

 piration, digestion, photosynthesis, and protein synthesis. 

 Although starting after anatomy, it has proceeded at a more 

 rapid pace. It was because of its tie-up with chemistry, itself 

 a rapidly growing subject, that physiology moved so fast. 

 As you will note from reading the articles, there is quite a 

 difference in the language used by Aristotle and Ingen-Housz 

 on the one hand and Went and Gray on the other. The 

 comparison is not as striking as it might be because the latter 

 two articles were especially selected and abridged for ease of 

 reading. Modern physiological papers are very complicated. 



The study of respiration in yeast cells has had important 

 applications in our knowledge of human muscle fatigue. Since 

 plants are the most important sources of vitamins, much 

 attention has been paid to vitamin synthesis. Protein syn- 

 thesis in peas and beans is being studied and this will help us 

 in understanding the situation in human beings. The day 

 is almost certainly coming when food chains will have to be 

 shortened as a matter of efficiency, and man may get his 

 proteins from plants entirely. A Kansas City steak may con- 

 sist of peas and soybeans in the future, truly a gruesome 

 thought. 



However, the project upon which full speed is underway 

 is the solution of the photosynthesis puzzle. How can a 

 miserable dandelion make all of the sugar needed from a 

 common gas, carbon dioxide and a common liquid, water? 

 All of man's food, directly or indirectly, must come as a re- 

 sult of photosynthesis. If the plant physiologists can produce 

 sugar in commercial quantities as does the dandelion, one of 

 our most pressing problems will have been solved. 



For more papers on physiology, see the book Great Ex- 

 periments in Biology by M. L. Gabriel and S. Fogel and in 

 The Life of the Green Plant by A. W. Calston. 



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