ALG^. 1 2 



J 



they do not increase by cell division, but they can 

 and do enlarge themselves as they progress towards 

 maturity, each as a separate and independent indi- 

 vidual. The cells are cylindrical, like rods, usually 

 a little thickened at each end, containing an inner 

 cylinder of green chlorophyl, floating in a watery 

 fluid, and containing starch granules. The number 

 of meshes, or rods, contained within an entire colony, 

 or net, is just the same when full-grown as in an 

 infantile state. The cell wall is double, the outer 

 being a very thin membrane, and the inner more 

 mucilaginous. The chlorophyl layer encloses the 

 starch granules, which increase in number with the 

 age of the cell, being at first only one or two, but 

 finally several hundreds. 



There is no sexual reproduction known, but the 

 continuance of the species is provided for in two 

 ways ; that is, by the large gonidia, and the small 

 gonidia, each with a separate history. The large 

 gonidia are not so very much larger than the small 

 gonidia, but they are concerned in the direct forma- 

 tion of the young net. The former are from seven 

 thousand upwards in a single cell, the latter from 

 thirty thousand. Braun says that " if a single fully 

 developed net, or even fragments of nets, are placed 

 in a shallow saucer of water, we may almost certainly 

 reckon upon finding fully formed young nets in some 

 of the old cells, on the next, or at all events on the 

 second morning, and these in cells which exhibited 

 no alteration whatever. If we wish to see the origin 

 of these young nets we must not lose the earliest 

 hours of the morning, for the tremulous movement 



