366 Profs. King and Rowney on 



of serpentine penetrating a matrix of carbonate of lime ; ' and 

 we are now quite ready to accept his latest and additional 

 statement — that it j^resents the serpentinous threads ' often 

 slightly bulbose at their extremity,' as in our paper on the 

 Skye ophite an additional figure is given representing a few 

 ' nearly parallel cylindrical processes ' attached to the curving 

 edge or surface of a piece of serpentine (' chamber-cast '), and 

 which before decalcihcation ' traversed the carbonate of lime,' 

 forming the ' true cell-wall.' Two of the processes stand out 

 conspicuously ; three of the smaller ones are also conspicuous ; 

 but the remainder are obscurely defined. It is remarkable 

 that one of the largest is '■ slightly bulbose at the extremity ' ! 

 As the example shows no appearance of sharp angular needles 

 radiating from a centre or irregularly disposed, it must be 

 taken to represent the true cell- wall. If our position is denied. 

 Dr. Dawson will have to support himself by something more 

 than gratuitous statements, or by weightier arguments than 

 such as he is in the habit of adducing." 



The describers of "^O0oow," though continually writing 

 about the " cell-wall," are exceedingly chary in giving any 

 definite or intelligible illustrations of it — nothing more in 

 general than figures exhibiting no proper distinction between 

 its so-called " tubuli " and the substance they penetrate. 

 * The Dawn of Life ' afforded an opportunity for making 

 ample amends for this neglect, especially as we have before 

 brought it under the notice of its author. It is an easy matter 

 to give a figure of the " casts of the tubuli " as exhibited in 

 decalcified specimens ; and they would certainly have been 

 more instructive than the diagram in page 106, or any of the 

 representations under figures 30a, 31 S, also 2, 3a in pi. viii., 

 all of which would equally stand for chrysotile ! But evidently 

 it is preferred publishing " extremely thin slices," as trans- 

 parent objects, in which " the best results can be obtained," 

 to giving representations of the " cell-wall " from decalcified 

 specimens, particularly such as show the casts of tubuli " glued 

 together by concretions of mineral matter," or those " specimens 

 which manifestly show the transition from the ordinary con- 

 dition of filling with serpentine to one in which the cell-walls 

 are represented obscurely by one shade of this mineral and 

 the cavities by another" (p. 114). The latter may not give 

 the " best results " in the estimation of Eozoonites ; but Dr. 

 Dawson must understand that the " scepticism of objectors " is 

 not " met " by such illustrations. Considering that they repre- 

 sent structures consisting of one of the most protean minerals 

 known to mineralogists, obviously whatever form serpentine 

 may occur under, that form ought to be most carefully examined 

 in all its relations. 



