134 Scientific Intelligence. 
while, again, others thought that I should be more successful with those 
which had in theory first suggested themselves to my own mind, name- 
ly the Chlorosperms. Afier making numerous unsuccessful experi 
ments with both the brown and red varieties of Algze, I was fully con- 
vineed that, under ordinary circumstances, the green weeds were the 
best adapted for the purpose. 
This point having been practically ascertained, and some good pieces 
of the Enteromorpha and Ulva latissima in a healthy state, attached to 
nodules of flint or chalk, having been procured from the shore near 
cessful experiments with the brown and red sea-weeds, to agitate and 
aérate the water, which had been rendered foul from the quantily of 
fitted for another experiment, it was, therefore, for greater convenience; 
removed into a shallow earthen pan and covered with a large glass 
shade to protect the surface of the water, as much as possible, from the 
dust and soot of the London atmosphere, and at the same time impede 
the evaporation. In this vessel then I had succeeded perfectly in keep- 
ing a large number of beautiful living specimens in a healthy condition 
up to the close of 1852. I therefore gave instructions for the making 
of a small tank as a more permanent reservoir, and one more adapie@ 
for carrying on my observations and investigations on the economy and 
habits of the inhabitants. hee 
From the experience I had obtained in my experiments with the 
freshwater tank, | was induced to modify slightly the construction of 
this vessel; thus, at the back, or part towards the light, the framing 
was filled with slate in the same way as the ends and bottom; for | he 
found that the glass, originally employed, very soon became covered 
with a confervoid growth whic d 
tank was covered with a light glass shade to keep out the dust and re- 
tard evaporation. 
With the sea water obtained in January, 1852, I have been working 
without cessation up to the present time, agitating and aérating when} 
i 
