PROF. OWEN ON A NEW SPECIES OF EUPLECTELLA. 121 
for by the solution of the gluten, to which act, perhaps, the greater transparency of the 
soaked fibril might be due. No diminution of diameter or other change of the fibril 
could be detected whilst it was under the action of the mineral acid. 
The fibrils of the Huplectella Aspergillum contain a greater proportion of organic 
matter, but have, as described in my original memoir, the same siliceous basis as in the 
present species. In consequence, however, of the different proportion of the glutinous 
and siliceous principles, they do not behave exactly like the fibrils of Euplectella Cucumer 
under the tests of heat and acid. In general, when subject to fire, they do not splinter, 
but merely bend; and when afterwards microscopically examined, show more trace of 
charring, and sometimes present increased opacity with the appearance of dead or frosted 
silver. Yet some show clearly their constitution of a siliceous sheath, including fine 
iridescent filaments or fibrillules. : 
It sometimes happened, in the case of fibrils of the Æwplectella Cucwmer submitted to 
the acid test, that a small amorphous mass would be adherent to part of a fibril; and 
such mass was quickly dissolved with the extrication of abundant gas-bubbles: the 
inference from this was, that some fragment of a foreign body of carbonate of lime had 
become accidentally entangled in the meshwork of the Buplectella. 
In the amorphous portions of sponge to which the Huplectella Cucwmer was connected 
by its long filaments, two modifications of reticulate structure were discovered by Dr. 
A. Farre. One, represented in Pl. XXI. fig. 8, is an irregular network, more or less bent, 
with subquadrate meshes, sometimes crossed by oblique threads. A second and more 
beautiful structure is represented in fig. 9. The meshes of this network are on nearly 
' the same plane, and of a more regular square form, with a short pointed spiculum pro- 
jecting from one side of each decussation of the threads, like the teeth of a harrow. Both 
figs. 8 & 9 give magnified views of the above structures, with the part magnified of the 
natural size. Fig. 9a gives a more magnified view of one of the squares, with its spines, 
of the * harrow’ structure. 
To the question put by almost every one to whom the Buplectella is shown, as to how 
the threads could have been so regularly yet intricately interwoven, I have sometimes 
replied, that there has been no such thing as interweaving in the case; that no thread, 
as such, was ever laid across another in the construction of the ÆEuplectella; that the 
analogy of human textile fabrics does not apply to this beautiful natural object. In 
artificial lacework the several stages of a complex result must be taken in the succession 
indicated by painful and exact calculation : in organic lacework different stages are done 
at once. Thus it is that the Divine works surpass those of man's utmost ingenuity. 
The threads of the Zuplectella were not first spun and then interwoven, but were formed 
as interwoven, the two processes going on simultaneously, or ‘pari passu? Just as in 
the cancellous texture of bone, the plates of bone are not first formed and then fitted to 
one another, as in building a house of cards; but the forming and the fitting go on 
together in the course of molecular growth. I presume also, that in the beautiful object 
which we call the Zuplectella, we have but its skeleton; and that, in the living state, 
d the exquisite structure of the flinty framework may be veiled by the delicate gelatinous 
enveloping organic tissue. 
VOL. XXII. 
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