294 On the Structure and Position of Eozoon Ganadense. 



in decalcified specimens — like the acicular layers occupying the 

 place of the proper walls of the chambers, — by their pure white- 

 ness, which contrasts strongly with the green of the serpentine 

 that has filled the cavities of the chambers ; and though this 

 might seem to indicate a difference in the infiltrating material, 

 no such difference really exists. I am informed by Sir William 

 Logan that Mr. Sterry Hunt has determined the chemical 

 identity of the two substances ; and hence it is obvious that 

 the whiteness of the internal casts of the tubes and canals 

 is due (like that of pounded glass) to the reflection of fight 

 occasioned by the fine division of their component particles ; 

 each rod, plate, stem, or branch, being composed of minute 

 asbestiform filaments, which represent, it would seem, so many 

 original threads of sarcode that partially coalesced to form 

 a bundle. Besides these definite shapes, however, we meet 

 in many decalcified specimens with large white amorphous 

 masses of like composition, occupying spaces which must have 

 been originally surrounded by the shell- sub stance of the inter- 

 mediate skeleton. The nature of these was for some time a 

 puzzle to me ; but I fortunately succeeded in gaining a clue 

 to their character by the decalcification of very thin sections 

 which had traversed them; and I find that they consist in 

 some instances of parallel lamellae disposed like the leaves of a 

 book, and in others of solid bunches of rounded filaments re- 

 minding one of a sailor's " swab ; " thus being in each case 

 but a mere aggregation of the elementary forms of sarcodic 

 prolongation already described. 



In those portions of the organism in which the chambers, 

 instead of being regularly arranged in floors, are piled together 

 in an " acervuline " manner, there is little trace either of 

 ' ' intermediate skeleton," or of ' ' canal-system " ; but the 

 characteristic structure of their proper walls is still unmistak- 

 ably exhibited, not only in transparent sections, but also in 

 decalcified specimens, wherever the asbestiform layer has not 

 been detached by the disengagement of gas from the surface 

 of the segment on which it should rest. 



The mode in which, in the regularly stratified portions of 

 the organism, each successive layer originated from the one 

 that preceded it, does not seem to have been always the same. 

 There is certainly no regular system of apertures for the 

 passage of stolons, giving origin to new segments, such as are 

 found in all ordinary many-chambered Foraminifera, whether 

 their type of growth be rectilineal, spiral, or cyclical ; and 

 although, when one layer is separated from another by nothing 

 else than the proper walls of the chambers, the coalescence of 

 the pseudopodia emerging from the upper surface of the last 

 formed layer would suffice to lay the foundation of a new layer 



