266 E. A. ANDREWS. 



were well set with new tubes (the wood was dried and sand- 

 papered before this experiment). The lowermost section of 

 wood reaching from the bottom up six feet showed tubes about 

 twenty to the square inch with but few in small clusters, but 

 the lowest two feet contained fewer and the bottom few inches, 

 none. The second section five feet long had as many, if not 

 more, tubes than the lowest section and more clusters, one con- 

 taining as many as 20 tubes. The third section was three feet 

 long and reached up above the surface of the water. The tubes 

 on it were as on the section below it but became very sparse 

 near the surface of the water. The fourth section floated out 

 diagonally in the water but was only partly submerged and it 

 contained but few tubes. 



In brief the tubes had been made on the strips of wood from 

 near the surface to within a few inches of the bottom, when there 

 were no plants near from which the animals might have migrated. 



It is thus evident that Folliculina occurs in greater depths 

 than the zones of vegetation in these creeks, but normally it can 

 find solids for attachment almost only within these zones, since 

 the region is without stones or rocks and with teredo fauna that 

 rapidly removes submerged woodwork. 



Folliculina is thus forced into association in depths with 

 Elodea and the few other flowering plants that follow the shore. 



SEASONAL DISTRIBUTION. 



These waters undergo great seasonal changes; in the high 

 temperatures of summer the water is turbid with microscopic 

 life, but more clear in winter. 



The grosser life of the plant zones along shore also rises to a 

 maximum in the summer and in the winter disappears down to 

 the bottom of the water where only the roots and pieces of stems 

 remain to revive in the following spring. 



Folliculina is thus forced into seasonal periods of abundance 

 and disappearance; but while it is abundant only with the 

 growth of the plants it has a much shorter period than they, 

 appearing in the summer after the plants are well started and 

 vanishing long before the plant zone dies down. 



In 1912 no live Folliculina could be found after September 8, 



