. A manual of zoology. Zoology. 9,9-) PORIFERA. fathoms). They form sjoherioal masses,, thin crusts, small cylinders, or upright branching forms. Frequently the shape varies so that one cannot speak of a typical form. It was also difficult to decide about the animal nature of the sponges. Striking movements of the body are rare; only by aid of the microscope can one see motion—the opening and closing of the pores and the streaming of tlie gastrovascular system. The simplest sponges, the Ascons (fig. 161), are thin-walled sacs, fixed at one end, and with an opening, the osculum (func- tional an
. A manual of zoology. Zoology. 9,9-) PORIFERA. fathoms). They form sjoherioal masses,, thin crusts, small cylinders, or upright branching forms. Frequently the shape varies so that one cannot speak of a typical form. It was also difficult to decide about the animal nature of the sponges. Striking movements of the body are rare; only by aid of the microscope can one see motion—the opening and closing of the pores and the streaming of tlie gastrovascular system. The simplest sponges, the Ascons (fig. 161), are thin-walled sacs, fixed at one end, and with an opening, the osculum (func- tional anus), at the other. The cavity of the sac, the ' stomach,' is a wide digestive cavity into which water bearing food obtains entrance through numerous small openings or pores in the body wall. The basis of the body is a homogeneous or fibrous connective. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
Size: 978px × 2556px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
