ALGAL FLORA OF THE MISSOURI BOTANICAL GARDEN. 41 



spores 21.4-28.8X48-80^, up to 3 diameters in length, ellip- 

 soid with rounded tips, conjugating the middle of May. 



Spirogyra porticalis (Miiller) Cleve. Fountain poncl. 

 Waterfall stream. Sept., through May. In an instance where 

 3 filaments lay parallel, the two outer filaments contained 



the central strand. 



aplanogametes 

 central strand 



1 



two zygospores, the cells of which showed connection with 

 cells of adjacent strands 



men 



indicative that the 



strands 



sex applies to the individual cell. Conjugation observed 



end of March. 



Spirogyra setiformis (Roth) Kutz. Nelumbium pools. 



Fairly abundant. Conjugating in November. 



This is the 



Spirogyra tenuissirna (H 



(D 



Kiitz. Arboretum pond. 



Mouaeotia scalane and Gonatonema 



to June. Conjugat 

 lateral and scalarifo 

 sociation of the 



tirough May. Conjugation is both 

 The receptive cell swells before dis- 



romatonhore of male 



the chromatophore. Chromatophore 

 cell is usually dissociated and ready to pass out of its cell 

 before the chromotaphore of the receptive cell has lost its 



form 



normal 



( apian ospores?) were found in one cell. These were some- 

 what smaller than the ordinary spores. 



MESOCARPACEAE. 



Abundant. 



Quiet 



Gonatonema sp. Typha angustifolia p 



Mougeotia scalaris Hassall. Arboreta 

 sociated with Spirogyra, Microspore Stici 

 ters. Conjugation observed Apr. 5. 

 gametes from one filament were conjugating with one from 



another adjacent filament to form a zygospore. 



In one instance 2 



VOLVOCALES. 



CHLAMYDOMONADACEAE. 



Chlamydomonas gloeocystif 



mud 



