. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF ASCIDIANS. 395 (Fig. 138, A, h); whether the primitive opening (Fjg. 386*, A, a) is closed or not, KowaleTsky says is an interesting question. According to analogy with many other animals it probably closes. The larva hatches in from forty-eight to sixty hours af- ter the beginning of segmen- tation, and is then of the form indicated by Pig. 386' (copied with some additions and omissions from Kupifer's figure, being partly diagram- matic). This anatomist dis- covered in the larva of ^s- cidia canina, which is more transparent tha
. Zoology for high schools and colleges. Zoology. DEVELOPMENT OF ASCIDIANS. 395 (Fig. 138, A, h); whether the primitive opening (Fjg. 386*, A, a) is closed or not, KowaleTsky says is an interesting question. According to analogy with many other animals it probably closes. The larva hatches in from forty-eight to sixty hours af- ter the beginning of segmen- tation, and is then of the form indicated by Pig. 386' (copied with some additions and omissions from Kupifer's figure, being partly diagram- matic). This anatomist dis- covered in the larva of ^s- cidia canina, which is more transparent than Kowalev- sky's Phallusia larva, not only a central nervous cord overlying the chorda dorsalis and extending well into the tail, while in the body of the larva, it becomes broader, club-shaped, and surrounds the sensitive cavity (a), but he also detected three pairs of spinal nerves (s) arising at regular intervals from; the spinal cord (A, h') and dis- tributed to the muscles (not represented in the figure) of the tail; Kupffer calls / the middle and g the lower brain- ganglion. The pharynx (5), or respiratory sac, is now very large ; it opens pos- teriorly into the stomach and intestine {i); x represents one of the three appendages itself to some object when about to change into the Fig, 388*.—Larval Ascidian. a, sense cavity containing the eye; 6, pharynx or c, notochord; respiratory sac: uditory org £, supposed auditory organ ; /, middle, g, lower brain- ganglion \ h, h, spinal cord ; «, «, «, three setff of spinai nerves; i, intestine; t^ body-wall, consisting of epithelial cells.— Copied with some changes from Eupfler, by which the larva fastens. 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 Packard, A. S. (Alpheus Spring), 1839-1905. New York, H. Holt and Company
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
