^98 Mr. Toulmin Smith on the Formation 



Not one of the arguments and points thus enumerated, and 

 minor ones might have been added, is attempted to be answered 

 by Mr. Bowerbank. That fact naturally gives them much addi- 

 tional weight, as his paper is an avowed " reply ^^ to mine, and 

 all that could be answered would assuredly be so : — Expressio 

 unius est exclusio alterius, 



4. Let us now see how points really touched on, and bearing 

 on the question, are handled. 



On page 250 there is an attempt to reconcile the facts of the 

 unequal distribution of the sponge spicula [their " suspension in 

 all parts alike ^^ (see page 252*) is a thing which does not exist] . 

 When I speak of the '^ destruction of the structure of the sponge,^^ 

 I of course allude to the "tissue" so often named; though, 

 whether this or the gelatinous matter be meant, it is equally 

 certain that its destruction is a necessary postulate of the sponge 

 theory, inasmuch as, if not destroyed, it would be still present ; 

 but no single instance exists in which that tissue has been found 

 to pervade the whole substance of any flint ; and this must be ob- 

 vious to every one familiar with the phsenomena, notwithstanding 

 that Mr. Bowerbank now " denies totally f" this destruction of 

 structure. It is admitted, in this very passage, that the " horny 

 skeletons are very enduring," and see further page 258. This 

 fact then necessarily implies, what I have shown to be incon- 

 sistent with fact, and what the author himself elsewhere now 

 denies, viz. the long- continued gelatinous state of the flint to 

 allow of the decomposition of this tissue to such an extent that 

 only the fragmentary remains we have of it shall be left. Mr. 

 Bowerbank tells us that the spicula exist in the gelatinous sub- 

 stance. Dr. Johnston, on the contrary, describes those spicula 

 as " bound together by a substance analogous to horn or albu- 

 men," either in the form of fibre or difi'used, this horny matter 

 being the very substance described by Mr. Bowerbank as so- 

 ^' very enduring ;" so that the spicula ought clearly to be retained 

 in their position, and not to run away in the poetic manner ima- 

 gined by Mr. Bowerbank. Besides this, Mr. Bowerbank tells 

 us { that the mealy coating of flints is formed by the penetration 



* See also * Geol. Trans.,' vi. p. 181. This very assumption is also ob- 

 viously inconsistent with the explanation now offered at p. 250. 



f Ehrenberg expressly says of the Paramoudras, that he ^'failed to dis- 

 cover in the interior the structure of well-preserved sponges;" and further, 

 that "the internal structure does not in any way favour this view" of their 

 spongeous origin. This is not an unimportant testimony. See 'Ann. Nat. 

 Hist./ vol. ii. pp. 161 and 162. In the * Geol. Trans./ vol, vi. p. 183, Mr. 

 Bowerbank himself says, that often " no indication of the former presence 

 of the organized structure of the sponge remains." What are we to under- 

 stand by such contrary and contradictory propositions? 



X Trans. Geol. Soc. vol. vi. p. 184. 



