. Animal studies. 124 ANIMAL STUDIES (and known as green glands), as in the crayfishes or crabs, or on the second maxillae (shell-glands) in many of the. Fig. 71.—Dissection of crayfish, b, brain ; h, heart; i, intestine ; k, kidney ; I, liver ; n, nerve-cord ; r, reproductive organ ; s, stomach, showing two teeth in position. simpler crustaceans. Their method of operation is much like that of the kidneys in the earthworm. 117. Nervous system and special senses.—The nervous sys- tem also shows a decided resemblance to that of the anne- lids. The cerebral ganglia or brain is situated above the
. Animal studies. 124 ANIMAL STUDIES (and known as green glands), as in the crayfishes or crabs, or on the second maxillae (shell-glands) in many of the. Fig. 71.—Dissection of crayfish, b, brain ; h, heart; i, intestine ; k, kidney ; I, liver ; n, nerve-cord ; r, reproductive organ ; s, stomach, showing two teeth in position. simpler crustaceans. Their method of operation is much like that of the kidneys in the earthworm. 117. Nervous system and special senses.—The nervous sys- tem also shows a decided resemblance to that of the anne- lids. The cerebral ganglia or brain is situated above the alimentary canal in the head, and connects with the ven- trally lying cord by a collar. As in the earthworm, this ventral cord is double, and bears a pair of swellings or gan- glia in each segment. In the crayfish, crabs, and other highly modified forms, where the segments tend to fuse,' several of these ganglia may also unite, and except in early life their number cannot be determined. Among the less specialized Crustacea the order of intel- ligence is low, though perhaps it may prove to be higher than is usually supposed when such forms have been more thoroughly studied. The following quotation relating to the lobster applies even more to the higher forms, the crabs : " Sluggish as it often appears when out of water and when partially exhausted, it is quite a different animal when free to move at will in its natural environment on the sea-. 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 Jordan, David Starr, 1851-1931; Kellogg, Vernon L. [from old catalog].
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Keywords: ., bookauthorjordanda, bookcentury1900, bookdecade1900, bookyear1903
