48 THE BIOLOGY OF THE CELL 



Boil a small amount of Pasteur's solution or of 

 dilute prune-juice, and with a glass rod, which 

 just before using has been passed slowly through 

 the flame of an alcohol lamp, transfer a drop of 

 the fluid to the surface of a cover-glass which 

 has likewise been passed through the flame ; have 

 ready the glass slide, which previously has been 

 sterihzed in the same manner, and lay on it the 

 card-board cell or glass ring, which has been ster- 

 ilized in boiling water; invert over the cell as 

 quickly as possible the cover-glass with the hang- 

 ing drop, and after making sure by microscopic 

 examination that spores, drop, etc., are in good 

 condition, set the slide away under a beU-jar in a 

 warm place. Note how the spores sprout. How 

 long before the process begins? What is the 

 first indication that a sprout is forming? How 

 does the size of the tubes put forth compare with 

 that of the spores ? How do you account for the 

 difference ? 

 Make drawings to illustrate different stages of germi- 

 nation. 



General Questions. — Upon what do the spores depend 

 for their dispersal ? How do you account for the mould- 

 ing of bread, pastry, leather, ink, etc., in warm, damp 

 weather? Why does it not also happen as frequently 

 in cold weather ? How is it possible for fruit in closed 

 cans to become mouldy ? 



Example 4. — Pollen Grains 



Material. — The best plan will be to get pollen from a 

 number of flowers and make a comparative study. It 



