[Vol. 6 



302 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Series A, inoculated with very poor soil from the Missouri 

 Botanical Garden, was a preliminary series and not carefully 

 examined, so that no record is tabulated. Cultures were taken 

 at the surface and at 20, 40, and 60 cm. below the surface. 

 Protoderma viride was found in all the cultures and Anabaena 

 appeared in those taken at a depth of 20 cm. 



Series H contained a greater number of blue-green forms 

 than any of the other series, and it seemed desirable to repeat the 

 experiment. Series I was inoculated March 6, and Series J, 

 June 27, 1919, with soil taken within a few centimeters of the 

 area used in Series H. The surface of the embankment was 

 scraped off to expose a clean area. At the end of 3 months in 



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Series I, and 40 days in Series J, no growth was apparent, whereas 

 in Series H growth had been abundant in almost all of the 

 bottles in the latter period of time. 



Since Series I showed no growth at the end of 90 days, the 

 cultures were discarded. Growth in Series J first appeared at 

 the end of about 40 days. Even at the end of 3 months these 

 cultures showed less growth and fewer species of algae than those 

 of Series H. However, Protoderma viride again appeared 

 throughout. The fact that there was no growth in Series I and 

 that fewer species of algae appeared in Series J may have been 

 due to the surface of the embankment having been exposed 

 during the winter months and the low temperature probably 

 having killed some of the form:? originally present in Series H. 

 This exposure probably killed many or all of the vegetative 

 cells of the algae which survived, and thus the delayed growth 

 in Series J might be explained by the persistence of spores which 

 required a longer period of time in which to produce a visible 

 growth. 



The cultures of soil from Woods Hole, Mass. and Santa Ana, 

 Calif, were taken in exactly the same manner to a depth of 1 

 meter as the preceding ones. The soil at Woods Hole was sandy 

 gravel containing several large boulders. The series taken at 

 Santa Ana were especially valuable because of the different 

 soil conditions, one series being taken from very sandy soil 

 and another from sandy alkali soil. The third series was taken 



