26 E. G. PRINGSHEIM 



Of larger Chlorophyta, Cladophora, Vaucheria, Hydrodictyon, 

 Eremosphaera, various Chaetophorales, and a great many other 

 forms give no difficulties. 



EUGLENOPHYTA: Every species could be grown w^ith the 

 exception of Euglena obtusa Schmitz (syn. E, limosa Gard). 

 which lives on periodically flooded mud flats. All the other 

 species of Euglena as well as Eutreptia, Phacus, Lepocinclis, 

 Trachelomonas, Cryptoglena, Colacium, and other species of the 

 colorless genera, Astasia, Distigma, Meiioidium, Rhabdomonas, 

 Hyalophacus, Cyclidiopsis, Entosiphon, Peranema, and others 

 grew well from single cells. Contrary to these results and in spite of 

 repeated efforts relatively few Euglenophyta have been grown so 

 far in pure culture; namely a few species of Euglena, Trachelomo- 

 nas and Colacium, and apochlorotic races of Euglena gracilis 

 Klebs. 



CYANOPHYTA: These are developed extraordinarily well 

 in soil-water cultures, most of them preserving their color and 

 natural appearance for a long time, especially upon addition of 

 ammonium-magnesium phosphate. Specis of Spirulina, including 

 the rare colorless vS". albida Kolkwitz, as well as Beggiatoa, multiply 

 well. 



Among the peculiar forms believed to contain symbiotic Cyan- 

 ophyta as chloroplast substitutes, Cyanophora paradoxa Korsch. 

 and Glaucocystis N ostochinearum Itz., the only ones found, 

 could be grown in uni-algal cultures. Various Ciliata and Spiril- 

 lum volutans, the largest species in the genus, never grown in 

 pure culture, can also be maintained regularly. 



Experience shows that the soil-water technique, although not 

 a substitute for pure cultures, has definite advantages coupled 

 with drawbacks. Its simple application recommends it to those 

 phycologists who have no bacteriological training nor equipment. 

 To the ecologist and physiologist it offers new problems but 

 also a new road of approach. 



