. Fresh-water biology. Freshwater biology. (7) Gray or brown; four kinds of nematocysts, diameter of largest less than mm.; embryonic chitinous membrane plano-con- vex, with only convex side covered with spines; spermaries limited to the oral third of the body; sexual activity more frequent in auttimn Hydra polypus Linnaeus 1758. Besides the differences between H. oligaciis and .0". polypus mentioned above the latter is said to be somewhat smaller and to have somewhat shorter tentacles than the former. By some the validity of any of the differing characters mentioned above is dispute
. Fresh-water biology. Freshwater biology. (7) Gray or brown; four kinds of nematocysts, diameter of largest less than mm.; embryonic chitinous membrane plano-con- vex, with only convex side covered with spines; spermaries limited to the oral third of the body; sexual activity more frequent in auttimn Hydra polypus Linnaeus 1758. Besides the differences between H. oligaciis and .0". polypus mentioned above the latter is said to be somewhat smaller and to have somewhat shorter tentacles than the former. By some the validity of any of the differing characters mentioned above is disputed, with the possible exception of the difference in the number of different kinds of nematocysts. B. pallida Beardsley, a very pale form in Colorado, and H. corala Elrod, a very large red form in Montana, may prove to belong to the species listed above, as similar variations of them are known to occur in Fig. 585. Bydra polypus, (a) Nematocysts. {b) Embry- onic chitinous membrane. X 36. (After Brauer.) 9 (2) Tentacles irregularly scattered on the body of the hydranth; form true colonies Cordylophora Allman. But one species, C. lacustris Allman, which occurs in fresh water near Philadelphia, Pa., and near Woods Hole, Mass. It has recently been found in the Illinois River at Havana, and by Mr. W. Donaldson in the Mississippi River at Granite City and East St. Louis, 111., in the Arkansas River at Little Rock, Ark., and in the Red River at Shreveport, La. Fig. s86. Cordylophora lacustris. {a) A branch from a colony. About twice as large as is common in fresh water. (6) Female reproductive zooids with embryos in different stages of development. X 20. (After Schulze.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ward, Henry Baldwin, 1865-1945; Whipple, George Chandler, 1866-1924. joint author. New Yo
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
