. Fresh-water biology. Freshwater biology. CHAPTER XVIII GASTROTRICHA By henry B. ward Professor of Zoology, University of Illinois Among the microscopic animals common in fresh water and Umited in distribution to that environment are certain minute organisms known as the Gastrotricha. Though limited in variety of species they are so abundant, so widely distributed, and so strik- ing in appearance as to command the attention of every student of aquatic life. They live in numbers among algae and debris and in almost every bottom collection appear in company with the rotifers and protozoans. In
. Fresh-water biology. Freshwater biology. CHAPTER XVIII GASTROTRICHA By henry B. ward Professor of Zoology, University of Illinois Among the microscopic animals common in fresh water and Umited in distribution to that environment are certain minute organisms known as the Gastrotricha. Though limited in variety of species they are so abundant, so widely distributed, and so strik- ing in appearance as to command the attention of every student of aquatic life. They live in numbers among algae and debris and in almost every bottom collection appear in company with the rotifers and protozoans. In movements and habits they resemble closely the ciliate Protozoa, and are easily confused with them. Ehrenberg, who first described in detail the structure of these organisms, placed them among the Rotifera and many later investigators have followed this suggestion. Others incline to regard them as Nematoda from which they differ most strikingly in pos- sessing cilia which are not known in other worms of that group. In size they are strictly microscopic, varying fr'^m mm. in maxi- mum length to only one-eighth of that. They constitute a distinctly uniform group not closely related to any other existing types of animal life. Our knowledge of the anatomy of these organisms is due principally to the ,• ,- r cj. 1 ;_ w-T-*^ i- ] Chaetonotusmaximus mvestigations of Stokes m this country and in ventral view. £1, kidney, „ ,. 1 . r~i ; J,brain:£.egg, Zeunka m Germany. 0, esophagus; /, intestine-, „, , , , p ,1 • „ 0«, ovary. X 400. (After The general structure of the group is well zeiinka.) illustrated in the figure of Chaetonotus maximus taken from Zelinka's monograph (Fig. 963). While the form of the body approacbt;s a cylinder, there is usually an expanded area in front known ai lb** 621. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfreshwa, bookyear1918
