6o 



GEXERAL BIOLOGY 



The two studies -which immediately follow are intended 

 to give i) an acquaintance with the appearance of the living 

 part of plant substance, and 2) some knowledge at first 



hand of the diversity of form of cells and 

 of the manner of their combination to- 

 gether into a plant body among the algae. 



Study 8. The cell of Spirogyra and the 

 protoplasm of Nitella. 



Materials needed — a supply of fresh 

 Spirogyra and Nitella in clean water. 



Apparatus needed — the usual labora- 

 tory equipment of simple and compound 

 microscopes, small tools, glassware and 

 reagents. 



The student should first examine Spir- 

 ogyra in mass, as it lies in the water, and 

 then lift out a small tuft of its long 

 filaments for examination in water upon a 

 white plate. He will there note their 

 length and their unbranched condition. 

 Examining them with a simple lens, he 

 will be able to distinguish clearly the 

 spiral bands of green that wind about each 

 filament on the inside and make Spirogyra 

 easy of recognition among other algae of similar manner of 

 growth (fig. 44). 



If he then mount a few filaments upon a slide, placing a 

 cover-glass upon a favorable portion, and filling up the 

 space beneath the cover glass with water, he may with 

 advantage apply the compound microscope to the ex- 



FlG. 44. Spirog^^ra. 

 a, a bit of a filament 

 containing nine 

 cells; 6, a single cell, 

 more highly magni- 

 fied ; c, cytoplasm; 

 n, nucleus; p, pyre- 

 noids, in the chloro- 

 phyl band. 



amination of them.* 



Placing 



the slide thus prepared 



*If the student be not familiar with the use of the compound 

 microscope, let him at this point pursue the supplemental study 

 outlined in the opening pages of the appendix, for which Spirog^^ra is 

 appropriate material. 



