1919] 



MOORE AND KARRER A SUBTERRANEAN ALGAL FLORA 305 



and het 



Artificial Subterranean Cultures 



Very little work has been done on the effect of subterranean 

 conditions upon the growth of algae. In studying the effect 

 of light, culture media have been used which did not duplicate 

 soil conditions. Esmarch determined the effect of light upon 

 the growth of certain Cyanophyceae which he found in subter- 

 ranean cultures. As shown above, these algae were grown on 

 soil in the dark and examined from time to time. From his 

 results, he concluded that these forms could live in darkness for 

 a short period of time but after several weeks, in most cases, 

 the cells showed effects due to the absence of light. The extent 

 of this effect depended upon the nature of the soil and individual 

 characteristics of the alga. Eventually only spores 



cysts remained. 



Since Protoderma viride was found to be universally present in 

 the cultures, an attempt was made to determine the effect of 

 subterranean conditions upon its growth. The foregoing results 

 showed that it could exist in undisturbed soils for a depth of 

 one meter at least, thus being capable of living for long periods 

 of time in the absence of light. In order to determine the effect 

 of these conditions upon its growth, the following experiments 



were performed: 



One culture was set up January 15, 1919. A small amount 

 of sterile clay was put into a sterile glass cylinder about 2 cm. 

 in diameter and 1 m. long. The soil was moistened with 

 sterile water and a piece of sterile filter-paper that had been 

 inoculated with Protoderma derived from culture H9' was 



placed 



of soil, moistened with 



and inoculated filter-paper were added until the tube was filled. 

 A sterile cotton plug was used to cork the top, so that some 

 aeration could take place. The tube was then sunk in the 

 ground to the depth of 1 m., thus allowing the culture to grow 

 under somewhat natural conditions. A flower-pot was placed 

 over the top to protect the cotton plug. 



Other cultures were set up on February 1, 1919. The actual 

 aeration conditions occurring in the soil were more nearly dupli- 

 cated in these than in the previous culture, since small sterile 



