THE PLANTS OF THE SEA. 31 
the water containing this substance, and with a spoon he filled 
a glass. The following day it had become a deep violet, and 
the water a rose tint. By straining the water through linen, the 
substance adhered to the cloth ; when dry it became green. This 
M. Montague examined, and pronounced it to be a minute 
sea-weed of the same kind as the preceding one. He named it 
THE PERFORATED THALASSIOPHYLLUM. 
Trichodesmium Ehrenbergit. This algee is composed of articulated 
fibres, placed side by side, varying from z3oth to sdoth of an inch 
in length. The microscope shows that the fibres are built up of 
cells fastened regularly end by end, firmly pressed together, and 
slightly four-sided. Other marine plants, on the contrary, present 
a gigantic size. Humboldt saw a fucus taken out of the water 
more than 500 yards long! 
The ocean plants do not bear much resemblance to those 
