[Vol. 6 

 284 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



character and mineral content of the soil as well as upon indi- 

 vidual differences of the algae themselves, the filaments became 

 discolored, passing from a pale blue-green through a yellowish 

 green to yellow. At first the contents of the cells appeared 

 normal and were apparently in a healthy condition. Later the 

 filaments disintegrated, leaving only spores and heterocysts be- 

 hind. Cultures which showed practically no normal filaments 

 were removed from the light-pro di case, the moistened filter- 

 paper placed on top of the soil, and after about 12 weeks' 

 exposure to daylight again showed blue-green growth. Esmarch 

 regarded this experiment as definitely indicating the impossi- 

 bility of blue-greens persisting beneath the surface for any 

 length of time, and considered that while the absence of light 

 was a factor, the destructive influence of the soil itself must be 

 taken into consideration. 



Aside from this paper of Esmarch's, there appears to be no 

 record of algae growing at considerable depths in the soil, and 

 the investigation here recorded — a preliminary announcement 

 of which was made at the Pittsburgh meeting of the Botanical 

 Society of America, on December 29, 1917 — is believed to be the 

 first definite indication that there may exist in the soil, at depths 



up to 1 



hich 



always present as a subterranean organism under conditi 

 which preclude its having recently been derived from the s 

 face and accidentally carried down to various depths. 



Methods 



The method employed throughout this study was essentially 

 the following: 



About 1^ inches of sand was placed in pint milk bottles, to 

 which was added 150 cc. of a culture solution. The bottles 

 were plugged with cotton and sterilized at 8-10 nounds 



pressure for \ hour. 



d 



strength of the formula of a modified Beyerinck's solution 

 used by Moore, 1 because of the soluble material present in 

 the sand. 



1 Moore, G. T. Methods for growing pare cultures of algae. Jour. Appl. Mi- 

 crosc. 6: 2309-2314. 1903. 



