King and Kowney — 
On " JEozoon CanadenseJ^ 
143 
others of the kind, have already been disposed of,"^' and ought not to have 
been a^ain introduced, unless supported by fresh and reliahle evidences. 
9th. We have always admitted that the true cell- wall presents 
minute cylindrical processes traversing carbonate of lime, and usually 
nearly parallel to each other," — even leforeJ)T. Dawson had published 
any description of them :f and we have throughout persistently used 
the term " acicuW for the casts of the tubuli ;" by which we wished 
them to be understood as having a cylindrical" form.J What is 
there to justify Dr. Dawson in again repeating that we confound the 
nummuline layer with fibrous and acicular crystals ?"§ l^o doubt Dr. 
Dawson has ''very often shown to microscopists and geologists the 
cell- wall with veins of chrysotile, and coating of acicular crystals oc- 
curring in Eozoonal limestone ; and that they have never failed at once 
to observe the difference;" but it may be allowed us to add that we 
could show them the originals of the cases figured in our papers, re- 
presenting intermediate examples graduating the "cell- wall," in its 
'' true" condition, into chrysotile ; also, the latter passing into struc- 
tureless serpentine. II ... It would now appear that Dr. Dawson will 
not admit many of the modifications described by Dr. Carpenter to re- 
present the ''cell-wall" in its various conditions of , formation ; but 
rather its accidental or mineral alterations. In such cases as the one re- 
presented in the Intellectual Ohserver, vol. vii., uncoloured plate, fig. 2, 
the "casts of the tubuli" are " glued together by concretions of mineral 
matter." This is one way of getting out of the difficulty ; but it is 
an escape from Scylla to be wrecked in Charybdis. Dr. Dawson has 
now no other alternative but to account for the disappearance of the 
calcareous portion of the " cell- wall" to enable the casts of the tubuli 
to become " glued together " by what is siliceous " mineral matter ;" and 
this involves our " singular theory of pseudomorphism" ! ... In our 
last paper, we accepted Dr. Dawson's first description of the "true 
cell-wall," as consisting of " slender undulating rounded threads of 
serpentine penetrating a matrix of carbonate of lime :" and we are now 
quite ready to accept his latest and additional statement — that it pre- 
sents the serpentinous threads " often slightly bulbose at their ex- 
tremity;" as we perceive something similar in the cylindrical threads of 
serpentine that line the walls in a true fissure.^ . . . It is our theory. 
* "Proceedings of the Royal Irish Academy," vol. x., pp. 522, 523. 
t Dr. Dawson has not, up to the present time, even given a representation of 
the "true cell wall." Indeed, this part has not yet been represented in any definite 
manner to illustrate its presumed typical characters, except by ourselves ! 
% " Quarterly Journal Geol. Soc," vol. xxii., p. 194. 
§ It must not be understood that we consider the aciculi to be in all cases 
"cylindrical;" because, having originated, as we believe, from prismatic fibres in 
the form of chrysi^tile, it is quite probable that they do not always lose their 
angularities. 
II " Quarterly Journal Geol. Soc," vol. xx., pi. xiv., figs. 1, 2, p. 92 ; " Proc. 
Royal Irish Academy," vol. x., pi. xli., fig. 1, 2, pp. 515, 516. 
U " Quarterly Journal Geol. Society," vol. xxii., pi. xiv., fig. 4. 
