34 MISSOURI BOTANICAL GARDEN. 



15, after which it sank to the floor of the pool. The free 

 floating or swimming forms of which the other representa- 

 tives consist seem scattered before this time, but when small 

 masses of the conjugating Spirogyra were examined spaces 

 between the filaments were found to be very abundantly filled 

 with these small algae. Here Conjugatae, Volvocaceae, Scene- 

 desmaceae and Flagellatae were represented. During the 

 early part of May just after the Spirogyra had disappeared a 

 large number of tadpoles made their appearance in the pool 

 and the remaining small algal forms rapidly approached the 

 vanishing point, the more abundant ones becoming rare. 



Crescent pool. This is a small pool of the shape of its 

 name with earth sides and floor and has no outlet. It con- 

 tains Acorus, Nymphaea, several species, and Nelumbium. 

 Observations were here taken during the spring, in the early 

 part of which one form was found in this place only, 

 i. e., Stigeoclonium glomerata. This pool contains more 

 Oscillatorias than the other pools. In the latter part of April 

 it was cleaned preliminary to the spring planting and the 

 only forms which endured were the group of Oscillatorias. 



Earth habitats. Those in which algae have been studied 

 are: 1. Vegetable garden, Botrydium Wallrothii and Proto- 

 siphon; 2. The mint beds, Botrydium Wallrothii; 3. Flower 

 beds near Fountain pond, Protosiphon botrioides, Chlorococ- 

 cum humicola, Oscillatoria animalis and Stichococcus sub- 

 tilis; 4. Edge of Arboretum stream, Vaucheria sp. 



The soil of the first three locations is loess, moderately 

 moist ordinarily, occasionally becoming quite dry on the 

 surface. The fourth location is usually saturated, simply 

 mud. 



SYSTEMATIC ENUMERATION 



Schizophyta. 



SCHIZOMYCETES. 



BEGGIATOACEAE. 



Beggiatoa alba (Vauch.) Trev. Stagnant water contain- 

 ing sewage or decaying vegetation. Arboretum stream. 



