88 MICROSCOPY FOR BEGINNERS. 



17. PENITTM. 



Cylindrical ; ends rounded, surface smooth. P. Bre~ 

 bissonii, Fig. 61. 



If it is desired to preserve any of the desmids or 

 Algae, the following solution will be found to be an ex- 

 cellent medium. In it the plants 

 retain their green color, and the 

 cell contents have less tendency 



Ffeei.-Pfiulnmlhebtarfoll. ^ ^^ ^^ ^ ^^ than 



with any other of the many media often recommended. 

 Any druggist can make the solution. It is composed 

 as follows : Camphorated water and distilled water, 

 of each 50 grammes ; glacial acetic acid, 0.5 gramme ; 

 crystallized chloride of copper and crystallized nitrate 

 of copper, of each 2 grammes ; dissolve and filter. 



The plants should be placed in a cell made of shellac, 

 a few drops of this preservative copper-solution added, 

 and the cover fastened down with shellac. If any other 

 cement, except perhaps Brown's rubber cement, is used 

 with this solution it will inevitably run under and ruin 

 the preparation. 



If the beginner should find the desmids so attractive 

 that he desires to study them rather than to learn the 

 names and appearance of a few of the commonest, he 

 should refer to the Kev. Francis Wolle's excellent book 

 entitled " The Desmids of the United States." 



