150 Botanical Microtechnique 



The preservation of green algae for bulk material and for perma- 

 nent stained slides is treated at some length in the chapter on whole- 

 mount methods. The advanced worker Avill find further details in 

 Johansen's (1940) comprehensive treatment of culture methods and 

 processing of this group. 



BLUE-GREEN ALGAE 



These algae have such simple cellular and colony organization and 

 are so easy to study in temporary whole mounts that the use of pre- 

 pared slides is less jtistifiable than with any other group of thallo- 

 phytes. Fresh cultures are easily found in a wide range of habitats; 

 in stagnant pools, tanks, barrels, and crocks, on potted plants with 

 stale soil, on damp, poorly drained soil, and innumerable other places. 

 Some forms like Oscilhitorid, Rivularia, Xostnc, and Gloeocapsa may 

 be found in masses that are practically pure cultures. Collections of 

 such materials are easy to preserve. Because of the dense undifferen- 

 tiated character of the protoplast the crudest methods of prcscr\ation, 

 such as 5% formalin, may be used. If the reagents are a\ailablc, one 

 of the fluids containing glycerin shotdd be used. Temporary or perma- 

 nent whole mounts can be made as described in Chap. 10. 



THE MARINE BROWN AND RED ALGAE 



I'he algae in these groups are available in fresh condition for a 

 very limited nmiibcr of schools. Large qiumtities of these plants are 

 used by schools that arc totally dependent on outside sources for their 

 materials. Therefore, a detailed discussion of methods of collecting 

 and preserving these plants woidd have but limited usefidness. For 

 occasional casual collecting on one's ira\els, the simplest preservative 

 is 5 to 10% formalin in sea water. Further rcfincnunts are the addi- 

 tion of 5 to 10% glycerin and 1/2 teaspoonful of borax to 1 liter of 

 fluid. 



For more critical picservatiou. nothing has l)ciii louiul to excel 

 chrome-acetic, with or wilhoui addition of osmic acid. One of the 

 best formidas is the Chamberlain foi inula ( Fable 3.1) made up with 

 sea water. Subsequent processing of filamentous loinis lor wliole 

 mounts is outlined in C.hap. 10. 



If materials are purchased from collectors, the purchaser shoidd 

 indicate whether the material is to be used for temj)orary slides or 

 to be processed for permanent j)ieparaii()ns. Sexcial relial)le collectors 

 will furnish material in specified stages ol the life history, carefidly 

 fixed in a suitable lluid determined by the collector or specified by 



