60 PARENCHYMA CELLS 



parenchyma tissue. Small simple pits may be visible in certain 

 walls of the cells. In order to understand the shape and propor- 

 tions of the parenchyma cells, as well as the intercommunication 

 between the prominent intercellular spaces, longi-sections of the 

 stem should be studied under low and high magnification. Ob- 

 serve that the intercellular space system in the longi-section 

 appears "black" because of the included air. This optical effect 

 is of great assistance in distinguishing between walls and longi- 

 tudinally exteuded air spaces. 



III. Suggested Drawings and Notes. — 



1. Prepare an enlarged drawing of a single cell from the 

 cotyledon of the bean seedling, showing its shape, wall structure 

 and the included starch grains. For comparison, draw several 

 cells from the cortex of the root of Bn'}n(nc}dus and the potato 

 tuber. Prepare notes on the differences in the form and structure 

 of the starch grains in these different examples. 



2. Prepare drawings, from both transverse and longi-sections, 

 showing-ihe structure of the photosynthetic parenchyma of the 

 cortex of the Begonia stem. Include cells which show crystals, 

 cytoplasm and chloroplasts. What conclusion do you reach as to 

 the shape of the parenchyma cells? Summarize, from the refer- 

 ences you have read, the method of origin and functions of inter- 

 cellular spaces in parenchyma tissue (cf. especially Turrell, 

 1936). 



REFERENCES 



1. Rloch, P., "Wound Healing in Higher Plants. Pot. Peview 

 7:110-146. 1!)41. 



2. De Bary, pp. 115-119. 



8. Eames and MacDaniels, pp. 52-54. 



4. Hay ward, p. 14. 



5. Marvin, J. W., Cell Shape Studies in the Pith of Eupatorium 

 purpurcum. Amer. Jour. Bot. 26 :487-504, 1939. 



6. Marvin, J. W., and Matzke, E. B., A New IMethod for the Con- 

 struction of Three-dimensional Cell IModels. Amer. Jour. 

 Bot. 26:101-103, 1939. 



7. Meyer, F. J., Das trophische Parenchym. A. Assimilations- 

 gewebe. IIandl)ucli d. Pflanzenanatomie. IV. 1923. 



8. Netolitzky, P"., Das trophische Parenchym. C. Speieher- 

 gewebe. Ilandbuch d. Pflanzenanatomie. IV. 1935. 



