48 LEAVES 
and there in cross sections of the leaf. These are cross 
sections of fibro-vascular bundles. Are the bundles in 
the leaf continuous with those in the stem and root? 
What is their function? Lay your sections aside. Do 
not destroy them. Strip a bit of epidermis from both. 
the upper and lower surface of a leaf. In the lower epi- 
dermis look for groups of cells forming elliptical rings, 
called stomata. How many cells do you find in a sto- 
ma? Draw one with the ceils surrounding it. Do you 
find any stomata in the upper epidermis ? Look for 
them in your cross sections. Note that each stoma con- 
tains an opening thru the epidermis. Into what do these 
openings lead? What is the function of stomatar Why 
does Elodea need none? Make an enlarged drawing 
accurately showing all the tissues of a leaf except the 
bundles. By means of iodin determine the cell contents 
as far as possible. 
Following the above outline, study a beech and 
begonia leaf and compare their histology with that of 
a iby dead, 
Literature. 
Bergen and Davis: Principles of Botany... 2.0006). .cue es 102-122 
stevens, Introduction to Botany i a eae 81-134 © 
Coulter: Text (Book).of.. Botamy yi a 16-40 
AUANSOR 8) FROTAINY re ia le yal ie al) ot AG CHI Ya a 35-80 
opaiding: Introduction to: Botany ee ics eae eae 61-73 
Bergen?) Foundations of Botany oi ee eee ee 150-177 
Bergen: Hlements''0f Botany! eee is Oe Ge 111-142 
Geddes. Chapters in Modern Botany........6 0.0000 c/ShAne 161-189 
Coulter Plant (Relations ole ieee sie sile bie eg ne Se Le 35-52 
Straspurgzer:) Practical: BOTA ie ss ae a 189-203 
etrasburger:’. Text Book ‘of Botany... Le ee 185-223 
PAV RSS VTE EFT ee eel a a UA a See index 
BeSSOy ee MEOW oie eee el te eisai ii Se ee a See index 
Kerner and Oliver: Natural History of Plants....... See index 
