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serious to the mind of the student, as there can he little doubt that in 
identifying species, the empirical taxology often with advantage takes the 
place of the natural one. The apertures of which we have spoken have 
two very distinct offices ; the smaller ones, which are termed po?'€s, bemg for 
the admission of water (containing air for respiration and food for digestion), 
which passes into the interior by the canals ; and the larger ones, which are 
termed oscula, allowing the used-up water to make its exit from the substance 
of the animal. Viewing all these characters in their tout ensemble, the writer 
thus defines a sponge ; — 
“ A fixed, aquatic polymorphic animal, inhaling and imbibing the sur- 
rounding element through numerous contractile pores, situate on the external 
surface, conveying it through internal canals or cavities, and ejecting it 
through appropriate orifices ; having an internal fiexible or infiexible skeleton, 
composed of either carbonate of lime, silex, or keratode, with or without 
either of these earthy materials. Calcareous skeletons always spicular ; 
siliceous skeletons either spicular, or composed of solid, laminated, and 
continuous siliceous fibre.” 
The description given of the several different varieties of spiculse is the 
most diffuse we have yet seen, and were it not for the immense number of 
technical terms (there being one for each form of spicule), would prove 
exceedingly instructive. We would not have it thought that in expressmg this 
opinion we are desirous of censuring the author. We believe there would be 
considerable difficulty (if, indeed, it were possible at all) in adapting ordinary 
language to define tersely the anatomical characters of certain organs ; a fact 
which botanists are well acquainted with. But being ourselves of opinion 
that the introduction of technicalities, while it does not advance philosophy, 
tends to trammel the popularization and diffusion of scientific knowledge, we 
regret to perceive the huge store of these formidable expressions with which 
the pages of Dr. Bowerbank’s work abounds. We refer more particularly to 
such terms as the following: — Dichotomo-patento-ternate ; clavato-attenuato- 
cylinclrical ; inflato-fusiformi-acerate; recurvo-dentato-hirotulate ; inequi- 
furcato-triradiate, &c. &c. The physiology of these creatures has been well 
worked out, and our author’s observations demonstrate to certainty their 
decided animality. This is perhaps more clearly seen in the examination 
of the oscula than in any other instance. 
“ The oscula are permanent organs, and are capable of being opened or 
closed at the will of the animal, and are subject to a considerable amount 
of variation in size and form, in accordance with the variation in the action 
of the sponge. Thus, in littoral sponges they are frequently entirely closed, 
and their situation even quite indeterminable during the period of their 
exposure to the air ; but when immersed in water, and the sponge is in the 
energetic action of the imbibition of nutriment, they are expanded to their full 
extent ; but when this action ceases, and that of gentle respiration only exists, 
many of them close entirely, and others exhibit apertures not exceeding half 
their former diameters while the imbibition of nutriment was in vivid action.” 
Dr. Bowerbank’s views concerning the nature of digestion in these the 
lowest members of the animal kingdom are of the utmost value ; and since 
he does not hesitate to express his conviction that the process of digestion 
here is identical with that which occurs even in man himself, the matter 
