Chlorophyceae 



179 



For laboratory cultures, select the forms found in quiet water, 

 but for preparations, forms growing where the waves dash hard are 

 better, since you can get a fine display of branches under a small 

 cover. Forms growing in still water or in gently flowing water may 

 look like unbranched filaments under an ordinary cover. In fixing, 

 use rather weak solutions. A chromo-acetic acid solution with 1 g. 

 of chromic acid and 4 c.c. of glacial acetic acid to 400 c.c. of water 

 will usually produce no plasmolysis, and will fix the material in 24 

 hours. After washing in water, stain some of the 

 material in iron-haematoxylin and put it into the 

 10 per cent glycerin; also put some material in 

 without staining, reserving it for the Magdala red 

 and anilin blue. The iron-haematoxylin material 

 will give better views of the nuclei and pyrenoids, 

 while the other stain will give better views of the 

 other cell contents and the cell walls (Fig. 40). 



Chara. Chara is found in ponds, lagoons, and 

 ditches. Once seen, it is always readily recognized 

 (Fig. 41). In the* ponds and lagoons along the 

 southern shores of Lake Michigan it fruits so 

 abundantly that the whole pond shows an orange 

 color due to the immense numbers of antheridia. 

 In the lagoons of the Chicago parks Chara is so 

 abundant that it must be dredged out every 

 summer. 



and stained in iron- 



Chara is easily kept alive throughout the year a ium haematoxyiin. 

 in the laboratory. A two-gallon glass jar with an 

 inch of pond dirt, sand, and gravel at the bottom, and nearly filled 

 with tap water, is all that is needed for a successful culture. If the 

 jar is to be covered, it should not be more than two-thirds full of 

 water. Not more than a dozen plants should be put into such a jar. 



A rather strong solution should be used for fixing. The following 

 will give good results: 



Chromic acid 1 g. 



Glacial acetic acid 1 c.c. 



Water. 100 c.c. 



* . ? > , / 



FIG. 40. Clado- 

 phora: fixed in 

 chromo-acetic acid 



