. The life of inland waters; an elementary text book of fresh-water biology for American students. Freshwater biology. Bfyozoans 167 nies are often large and conspicuous. Two of the commoner genefsi,' are shown in figure 76, riatural size. These may be found in every brook or pond, growing in fiat spreading colonies on leaves or pieces of bark or stones. Often a fiat board that has long been floating on the water, if overturned, will show a com- plete and beautiful tracery of entire colonies outspread upon the surface. New zooids are produced by bud- ding. The buds remain permanently attached,
. The life of inland waters; an elementary text book of fresh-water biology for American students. Freshwater biology. Bfyozoans 167 nies are often large and conspicuous. Two of the commoner genefsi,' are shown in figure 76, riatural size. These may be found in every brook or pond, growing in fiat spreading colonies on leaves or pieces of bark or stones. Often a fiat board that has long been floating on the water, if overturned, will show a com- plete and beautiful tracery of entire colonies outspread upon the surface. New zooids are produced by bud- ding. The buds remain permanently attached, each at the tip of a branch. With growth in length and the formation of a tough brown- ish cuticle over every por- tion except the ends, the skeleton of the colony devel- ops. This skeleton is what we see when we lift the leaf from the water and look at the colony—^brown, branch- ing tubes, with a hole in the end of each branch. Noth- ing that looks like an ani- mal is visible, for the zooids which are very sensitive and very delicate have all with- drawn into shelter. They suddenly disappear on the slightest disturbance of the water, and only slowly extend again. If we put a leaf or stone bearing a small colony into a glass of water and let it stand quietly for a time the zooids will slowly extend themselves, each unfolding a beautiful crown of tentacles. There are few more beautiful sights to be witnessed through a lens than the blossoming out of these delicate transparent, flower- like, crowns of tentacles from the tips of the apparently lifeless branches of a populus colony. They unfold from each bud, like a whorl of slender petals and slowly. Fig. 77. Three zooids of the bryo- zoan, Plumatella, magnified. I, expanded; m, retracted; «, partly re- tracted; », anus; j, intestine; ft, de- veloping Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illu
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1915
