ALGAL FLORA OF THE MISSOURI BOTANICAL GARDEN. 39 



aplanospores 



the earth had dried 



had 



observed 



end 



mmediately 



The aplanospores found earlier in the season on the earth 

 were studied directly from the earth and in drop cultures, 



f 



time. 



om 



earth were placed in water, they began to produce zoospores. 



mat 



divided into another generation of aplanospores within their 



setting the young ones free. They usu- 



broke 



ally remained agglutinized in a spherical group for a time, 

 then broke apart and grew to normal size. All of the young 



denned 



ma 



lar as the cells increased in size. 

 The aplanospores, then, may 



zoospores 



aplanospores, depending on environmental conditions, water 

 probably being the most important. The normal size of the 

 aplanospores up to the time of maturity as indicated by send- 

 ing out a rhizoid process or internal re-organization, is 



16— 38.4/*. 



Chloropbyceae. 



DESMIDIACEAE 



acerosum Ehrenb. Arboretum pond. 



in 



phaea pool. Nelumbium pools. . Crescent pool. Mar., May. 



Common. 



Closterium acerosum var. elongatum Breb. Arboretum 

 pond. Nymphaea pool. Nelumbium pools. Crescent pool. 



Mar., May. Common. 



Closterium Lunula var. intermedium Gutw. Lagoon. 

 Fountain pond. Arboretum pond. Sept., through Nov. 



Mar. to June. Rather common. 



Closterium moniliferum Ehrenb. Typha angustifolia pool. 



Lagoon. Oct., May. Rare. 



