CHLOROPHYCEAE 211 



very few take kindly to a sudden change of water. If the material has 

 been brought to the laboratory in a very small quantity of water, fill 

 the jar about two-thirds full with tap water. Let the water run for 2 

 or 3 minutes before you fill the jar, since the water standing in the 

 pipes is injurious, or even fatal, to most algae. Add water occasion- 

 ally, only a little at a time, to compensate for evaporation. If the 

 water has evaporated until the jar is about one-third full and you fill 

 it nearly to the top with tap water, you are likely to kill some of the 

 most desirable forms. 



It is a mistake to put too much material into a jar. A wad of 

 Spirogyra half as large as one's finger is as much as should be put into 

 a gallon jar. As it grows to ten or twenty times that amount, it is not 

 necessary to keep throwing it out, since it will gradually accommodate 

 itself to conditions; but if the larger amount should be put into the 

 jar when brought in from the field, it would die in a day or two. 



Cultures may be started even in the winter. A surprising number 

 of the green algae live through the winter under the ice of ponds and 

 rivers. Oedogonium commonly passes the winter in the sporeling stage. 

 Clado'phora may be found the year around. Coleochaete, on stems of 

 plants like Typha, can be taken from under the ice and, in a few days, 

 will be fruiting. Many pass the winter in the spore stage. 



Bring in some mud over which algae were growing the previous 

 summer or autumn; put it into a jar and fill it two-thirds full of tap 

 water. Also bring in sticks, leaves, and stones from good alga localities 

 and put them into jars of tap water. Cultures may be started either by 

 taking mud and sticks from under the ice or by taking them from places 

 which have entirely dried up during the summer or autumn. A few 

 such jars will be likely to yield a variety of material. 



If you have a good jar of Oedogonium, or some other desirable form, 

 do not throw it out if the alga should disappear. Remember that tem- 

 porary disappearances occur in nature. Allow the culture to become 

 dry and then set it aside where it will be protected from dust. After a few 

 months, pour on tap water and it is very likely that you will soon have 

 a good jar of Oedogonium. Many algae behave similarly; some, like 

 Volvox, appear for a short time and then disappear for a long time; 

 some, like Cladophora, may last the whole year, and grow so luxuri- 

 antly that the excess material must be removed; and some, like 

 Ulothrix, we have not been able to cultivate at all in the laboratory. 



Some very useful hints on collecting and growing fresh-water algae 



