Zoological classification : a handy book of reference with tables of the subkingdoms, classes, orders, etc., of the animal kingdom, their characters and lists of the families and principal genera / [Francis Polkinghorne Pascoe].

  • Francis Polkinghorne Pascoe
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: Zoological classification : a handy book of reference with tables of the subkingdoms, classes, orders, etc., of the animal kingdom, their characters and lists of the families and principal genera / [Francis Polkinghorne Pascoe]. Source: Wellcome Collection.

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    Class 1. SPONGIA. (Spongos.) Amorphozoa. Poripera. Polystomata. Spongozoa. Fixed aquatic organisms, composed of an aggregate of araoebi- forrn bodies, each provided with a mouth and numerous pores, and including a fibrous framework, strengthened by horny or cal- careous spicules. Larva} free-swimming. The gelatinous sarcode forming the animal mass of the sponge is made up of a number of individual masses of protoplasm [plas- tides], forming a thin outer layer and entering deeply into the organism, coating every cavity in the interior. The cavities are connected by canals, which are continuous with ciliated chambers. Minute chambers [pores or ostioles], through which the water passes into the cavities, exist on the outer layer, and the water so admitted is discharged by larger orifices [oscula].. It is to the vibratile action of the cilia that the circulation of the water is due. According to Huxley, the “ sponge represents a kind of sub- aqueous city, where the people are arranged about the streets and roads in such a manner that each can easily appropriate his food from the water as it passes along.” It is doubtful, however, whether the digestion is carried on by the general cells lining the passages or by the ciliated cells. By Leuckart and Hiickel the canal-system of Sponges is regarded as homologous to the gaBtrovascular system of the Hydrozoa and the Actinozoa. Furthermore, the Sponges and Corals are regarded as blood-relations, both originating [hypothetically] from a pri- mitive sac [protosaccus], the only morphological character sepa- rating them being the absence of urticating organs in the former. Thread-cells are, however, said to be found by Eimer in Reniera [these are by Carter declared to be parasitical polyps]. Eimer also considers that he has established a passage between Sponges and Hydroids. By Carter the relation of Sponges to Ascidians is regarded as greater than to Corals, the latter having only one aperture. Reproduction is either as exual by budding &c., or, in the Calci- spongiaj principally, by ova. According to Huxley, the embryo is ‘ similar to the corresponding stage of a hydrozoon, and is totally unlike any known condition of a protozoon.” The ova, so called by some observers, are supposed by Hiickel to be spermatozoa, or perhaps vibratile cells. Sponges are also reproduced by gemma- tion. The Gastrula stage is disputed by Barrois and Hyatt. According to Saville Kent, “ Sponges are compound, colony- building, collar-bearing, flagellate monads, exhibiting neither in C