1912] LEWIS—ALTERNATION IN FLORIDEAE 237 
the shells. This was usually done in the afternoon, and the algae 
taken out the next morning. The spores of most species were shed 
in abundance, the resulting sporelings becoming attached almost 
immediately. At first the dishes were kept in the laboratory till 
the sporelings had become about 2 mm. long, and the shells were 
then transferred to the waters of Vineyard Sound. In such cases, 
however, the sudden change of environment exerted a deleterious 
effect on growth. For this reason, in all the later experiments 
the shells were transferred on the second day after the spores were 
shed. This was found to allow ample time for firm attachment 
of the sporelings. Each shell, before being “ planted,” was minutely 
inspected with a lens, and only those were used which showed a 
good uniform “stand” of sporelings without visible contamination 
from the spores of other species. Close inspection was especially 
necessary in the case of Griffithsia and various species of the Rho- 
domelaceae, on account of the frequency in these forms of vege- 
tative multiplication from the broken off tips of the filaments. 
No attempt to thin out the sporelings was made. 
Tarred cord, first soaked for some months in salt water to 
extract the soluble matter in the tar, was used for attaching the 
shells. A sort of ladder was made by having two parallel cords 
about 6 inches apart, to which shells were tied by cord running 
from the three holes mentioned. A ladder prepared in this way 
was either stretched horizontally between two supports, such as 
stakes firmly driven into the bottom or allowed to hang vertically 
from a pile. In the latter case the parallel cords were weighted 
at the bottom, to prevent the ladder from becoming tangled by the 
tidal currents. The latter method proved more satisfactory, as 
in this way, by having a series of shells bearing sporelings of one 
species, the optimum depth for the growth of that species could be 
readily determined. This was found to vary with the species 
employed, but in general it was about 2-3 feet below mean low 
water. 
Plantations were made at Spindle Ledge, on the piles of the 
Government Wharf at Little Harbor, and on the piles at the end 
of the Fay Wharf. The best results were obtained at the last 
mentioned locality. The water here is very deep, the outermost 
