THE MICROSCOPE AND PLANT LIFE 



that it consists of a stalk terminated by a thin 

 walled portion, shaped like a bi-convex lens. Round 

 the edge of the greater part of this lens-shaped 

 portion there is a much more substantial-looking 

 rim. Within the lens-shaped part we can easily see 

 brown spores. If we have chosen our object at an 

 opportune moment, any excessive moisture in the 

 air will cause the thick-walled rim to straighten itself 

 out, tearing away the thin- walled, lens-shaped part 

 in so doing and setting free the spores. 



Closely related to the ferns, the horsetails provide I 

 another interesting object for the microscope. The i 

 fertile shoots of these plants, somewhat resembling i 

 asparagus, though in reality belonging to an entirely 

 different family, will, when gently tapped on a clean 

 dry microscope slide, leave behind a pale yellow 

 powder. The powder consists of spores, and most 

 interesting they are. When dry, each spore will be 

 seen to have four somewhat thread-like outgrowths, 

 flattened at the end ; breathe on the spores and each 

 of the outgrowths will coil up so as to form a com- 

 plete covering for the body of the spore. As dry-j 

 ing takes place, these outgrowths gradually uncoil | 

 again. | 



We have mentioned spores several times in this! 

 and other chapters. Strictly speaking a spore can- 

 not be compared with a seed, but for our purpose 

 it is sufficient to know that spores are more or less 

 seedlike in appearance and that they give rise to 

 new plants when they germinate. They are found h 

 in all ferns, on horsetails, these odd plants with 



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