238 BOTANICAL GAZETTE [MARCH 
piles standing in the edge of the main channel. The rapid flow of 
the tides, and perhaps other factors, seem to prevent the attach- 
ment of spores, so that the algal flora at this point is quite scanty. 
This was found to be of importance for the reason that shells placed 
here showed almost no contamination from unknown sources, while 
at the other localities foreign spores settled and grew so abundantly 
_and luxuriantly that the planted spores were overcrowded. Further- 
more, at Spindlé Ledge a considerable mass of drift, consisting 
for the most part of tangled mats of Ectocarpus, caught on the 
cords and prevented the development of the algae sown. In all, 
about 125 shells were planted. 
The plantations were all made in July. The shells were left 
in the water 21-45 days. It was found, however, that in those 
species in which definite results were obtained, little if any growth 
took place after August 15. On all shells taken up as late as Sep- 
tember 1, the algae were found to be disintegrating. After being 
collected, each shell was examined with the greatest care. Every 
visible growth, animal or plant, was scraped off and minutely 
inspected under the compound microscope. In this way possi- 
bility of error of observation was eliminated as far as could be done. 
In the course of the microscopic examinations, many observations 
were recorded as to the rate of growth of various species, the rela- 
tive abundance of spores at different localities, and other matters 
not included within the scope of the present paper. 
The following species were used: Spermothamnion Turneri 
Aresch., Callithamnion Baileyi Harv., Griffithsia Bornetiana Farlow, 
Ceramium rubrum Ag., Ceramium fastigiatum Harv., Cystoclonium 
purpurascens Kiitz., Chondrus crispus (L.) Stack., Lomentaria 
uncinata Menegh., Champia parvula (Ag.) Harv., Agardhiella 
tenera (J. Ag.) Schmitz, Grinnellia americana Harv., Gracilaria 
multipartita J. Ag., Chondria tenuissima (Ag.) Harv., C. dasyphila 
(Ag.) Harv., Polysiphonia fibrillosa Grev., P. violacea Grev., Dasya 
elegans Ag. (17 species). Of these, the majority proved to be 
unsuitable, definitive results being obtained only with Polysiphonia 
violacea, Griffithsia, and Dasya. The failure to obtain results with 
some was due to lack of proper environment, since no shells were 
planted in deep water where such forms as Gracilaria, Spermotham- 
