86 PLANT PHYSIOLOGY 



starch, drops of oil are produced in the cytoplasm and 

 cell sap, or cane sugar (Ci 2 H 2 20n) or some other 

 carbohydrates. 



126. The further fate of the carbohydrates formed in 

 photosynthesis is varied. The excess of glucose or other 

 sugars in the chlorophyll-bearing cells in addition to 

 what is put aside temporarily in insoluble form as starch 

 diffuses through the adjacent cells and finally reaches 

 the vascular bundles where it enters the parenchyma cells 

 bordering the sieve tubes. It probably diffuses through 

 these into the latter in which it diffuses and is probably 

 also carried by streams of protoplasm to those parts of 

 the plant where the tissues contain less glucose. 

 Here it diffuses out into these tissues. Besides passing 

 in the sieve tissues diffusion doubtless occurs from cell 

 to cell throughout the parenchyma of the cortex espe- 

 cially in those cells bordering on the sieve tubes. Dur- 

 ing the night the starch grains that have accumulated 

 in the chloroplasts in day time are transformed into 

 glucose which diffuses in the manner just described. 



127. The carbohydrates transported in this manner 

 may be stored up as reserve food in various forms. Thus 

 they may be transformed into starch in the leucoplasts of 

 the storage organs, e.g. tubers of potato, roots of sweet 

 potato (Ipomoea batatas), pith of various twigs such 

 as apple, sassafras, etc., medullary rays of many trees, 

 endosperm or cotyledons of seeds, etc. Cane sugar may 

 be found in many plants such as beets, maple, sugar cane, 

 etc. Inulin is found in the roots of many plants par- 

 ticularly those belonging to the order Aster ales. Trans- 

 formed into fats they are found in many seeds, e.g. flax, 

 cotton, peanut, castor bean, as well as in the bulb scales 

 of onion, leaves of cabbage, etc. In the seeds of many 

 palms, e.g. date, and the wood of many trees, e.g. elm and 



