. Elements of comparative anatomy. Anatomy, Comparative. 403 COMPARATIVE ANATOMY. A phenomenon worthy of the greatest attention appears in the Acopa in the disposition of the branchial slits, and is in the Salpas alone obliterated by the peculiarities of their organisation. This is the disposition of the slits in the manner of metameric structures. In Doliolum they form two rows of transverse clefts, and in Pyrosoma and Ascidians their transverse arrangement is also perceptible, although in the latter several or many slits occur in a cross series. Although this disposition is exhibited merely
. Elements of comparative anatomy. Anatomy, Comparative. 403 COMPARATIVE ANATOMY. A phenomenon worthy of the greatest attention appears in the Acopa in the disposition of the branchial slits, and is in the Salpas alone obliterated by the peculiarities of their organisation. This is the disposition of the slits in the manner of metameric structures. In Doliolum they form two rows of transverse clefts, and in Pyrosoma and Ascidians their transverse arrangement is also perceptible, although in the latter several or many slits occur in a cross series. Although this disposition is exhibited merely in a part of the gut, yet we are able to recognise in it a condition which supports the interpretation of it as an instance of metamerism. Metamerism exhibits itself here in fact without the participation of the entire organism, and it is not difficult to understand how, under certain conditions, other parts of the body might take part in it. § 311. The close relationship among themselves of all divisions of the Tunicata is further exhibited in the existence of peculiar organs belonging to the respiratory chamber which are connected with the nutritive functions of the animal. These organs are the ventral groove and the ciliated tracts. The ventral groove (hypo- branchial groove) (Fig. 211, Bn), also called En do style, is a groove lying in the ventral median line of the branchial chamber's wall, possessing up-standing margins (*) (ventral folds), and terminating B. 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 Gegenbaur, C. (Carl), 1826-1903; Bell, F. J. (Francis Jeffrey), 1855-1924; Lankester, E. Ray (Edwin Ray), Sir, 1847-1929. London, Macmillan and Co.
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