6 THE PROTOPLAST 



dicutyldedoii, noting the solitary crystals in tlie phloem paren- 

 chyma cells. 



V. Suggested Drawings and Notes. — 



1. Prepare an enlarged drawing of a single hair of either 

 squash or petunia as seen under low magnification showing ac- 

 curately the number and form of the cells of which it is com- 

 posed, and its mode of attachment to the stem. 



2. Draw a' single living cell of a hair as it appears under high 

 magnification. This drawing should portray a "median optical 

 view" and should include the following: cell wall, nucleus (and 

 its visible parts), cytoplasm, vacuole, plastids. Eccord, as lab- 

 oratory notes, all observations made on cytoplasmic streaming 

 and nuclear "movement" in the material studied. 



3. Select a cell from the "midrib" region of the Elodca leaf 

 and prepare drawings to show its appearance aud contents as 

 seen in surface and median optical views. Describe concisely 

 the variations in the rate and direction of cytoplasmic streaming 

 in cells at different regions of the leaf. What may be the physio- 

 logical significance of cytoplasmic streaming? Summarize the 

 evidence indicating that plastids do not arise dc novo m the 

 cytoplasm of plant cells [cf. Sharp (1934, pp. 69-72)]. 



4. Pi'epai-e drawings to illustrate the form and the ari-auge- 

 ment of chromoplasts in the material studied. 



5. Draw cells from the cortex of Pcllionia, the jxttato tuber 

 aud the bean cotyledon showing the size and form of the included 

 starch gr;iiiis. 



6. Prepcirc drawings lo show the foi'iii hiuI position of the 

 various types of crystals studied. 



RKFEREXCKS 



1. AiHl.Tsoii, T). n., TIic ShMicliuv of tlic Walls of the Ili-hcr Plants. 



Bol. K.'vi.'w 1 :r)-!-7(). l!);55. 

 '2. Kaiiics and MacDanicls, Cli. II, p. (5-1!). 



;{. iiahriiaiKit. cii. X. pp. r);5()-r).%. 



4. .Xctolitzky, F.. Die Kicsclkorper. Die Kalksal/.c als Zolliiihalts- 

 korjx'i'. llandhucli. d. Pflanzcnanatomio III. Berlin, 1929. 



f). . Das Iropliisclic I'arciicliyiii. ('. Spciclicvgcwcbc. 



IhirJ.. TV. Berlin. Pt.T). 



(i. Scliiiihdir, r. X. Die I'lastidcn. Ihi,l.. I. B.-rlin. 1!)24. 



7. Sliai')), L. W., Inlro(hicti()n to Cytoloj^y. .'Jd. cd. New York, 1934. 



8. W.'icr, E., The Striu-ture of tiieCldoroplast. Jiot. Kcv. 4:41)7-530. 

 1!)38. 



