Chlorophyceae 163 



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. However, do not let the jar 

 become choked with the material. 



Cultures may be started even in the winter. 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 desir- 

 able form, do not throw it out if the alga should disappear. 

 Remember that temporary 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 luxuriantly that the excess material must be removed; and 

 some, like Ulothrix, we have not been able to cultivate at all in 

 the laboratory. 



t/ 



Some very useful hints on collecting and growing fresh-water 

 algae for class work will be found in an article by Dr. J. A. Nieuw- 

 land in the Midland Naturalist, 1:85, 1909. 



Professor Klebs has shown that various phases in the life histories 

 of many algae and fungi may be produced at will. By utilizing his 

 results, the fruiting condition may be induced in many of the common 

 laboratory types. Knop's solution will be needed in most cases. 



