PUUBLE.M 22 51 



Heat the slide very slightly. Wliat is llic rcsuh ? (ool tlic 

 slide and note the effect on cell movenieiil. 



Conclusion. — 1. In what part of planls may j)n)t()pla>ni Ik; 

 found ? 



2. Write a paragraph, descri})in<2; tlic :ii)|)('aiaii('c. niovcnicnt, 

 and composition of protoplasm in Elodcu. \\ hat arc its rcdduniH 

 (look up this word in the dictionary) to heat and cold? 



Problem 21 : To study structure and groivth oj' iJoUcn. 



Materials. — Pollen of snapdragon, sweet i)ea, nit-^turtium, or 

 tulip; sugar solution (3 per cent, 10 per cent, and 1') per cent), 

 bell jar, sponge, a compound microscope, hand lens. 



Method. — ^Dust some pollen of snaptlragon on a glass sHde. 

 Examine it with a hand lens. Make a 10 per cent sohition of cano 

 sugar and dust some ripe pollen in a drop of the solution placed 

 on a glass slide. Place this slide under a small Itcll jai- with a 

 moist sponge and examine after 24 hours with the low j)owcr of 

 the compound microscope. Try sweet pea or nasturtium pollen 

 in a 15 per cent sugar solution, or tulip with a '-^ i)er cent su^ar 

 solution. 



Observations. — Look for a tubelike structure, the p<tUvn tiibe, 

 growing out of the pollen grains. Describe and sketch one. 



Conclusion. — 1. What made the pollen tulx^ grow? 



2. Under what other condition have you heard of the growth of 

 pollen ? 



Problem 22: To study the reason for the growth of jk,!! en- 

 grains in fioiuers. 



Method and Observations. — Study the following diagram, the 

 figures, pages 53 and 54, in your Civic HioUnjij, and charts 

 for further explanation. Within the pollen tube is a ceil known 

 as the sperm cell. Note that the cell in the end (.f the jxjllen 

 tube is about to unite with the egg. Observe the i)athway taken 

 by the pollen tube. How does the sperm cell from the i)ollen 

 grain get into the ovary? Study th(» longitudinal s.'ction of the 

 ovary. Note a number of ovoid bodies (ondcs) in the ovary. 

 How could a pollen tube reach an ovule ? 



