HARDWICKE'S SCIENCE-GOSSIP. 



«5 



Eozoon occurs ; the first locality from which it was 

 recorded was Burgess, in Ontario, but as many of 

 the best specimens have come from the Grenville 

 band of limestone at Cote St. Pierre, it will be better 

 to describe that. Eozoon occurs there, as a ser- 

 pentinized band of limestone, in a massive limestone, 

 interstratified between a layer of gneiss above and 

 a thick bed of diorite and gneiss below. (Fig. 38.) 



Many structures in these rocks Canadian geologists 

 considered had long given presumptive evidence in 

 favour of the existence of Laurentian life ; they pointed 

 to the vast beds of graphite (probably introduced as 

 liquid hydrocarbons) as representing the last stage 







n s 



m 



fmtMjjLiA 



Fig. 42. — Dawson's Restoration of Eozoon. 



— that beyond anthracite— in the metamorphism of 

 vegetable remains; they contended that the calcite 

 had been deposited by some organic agency like the 

 limestone beds of later date, and that the iron ores 

 were due to the reducing action of plants similar to 

 that of the Gaillonella ferruginca of the Swedish 

 lakes. 



The shell structure of the foraminifera need not 

 detain us long, as a mere recapitulation of its termin- 

 ology will suffice. The foraminifera, as everybody 

 knows, consist of simple masses of protoplasm, in 

 which is immersed a shell or "test," usually pene- 

 trated by a series of perforations, through which are 

 protruded extensions of the protoplasm termed 

 " pseudopodia." The shells are either chitinous, 



arenaceous (i.e. composed of grains of sand or such 

 like, bound together by a chitinous secretion), hyaline 

 or vitreous, or calcareous. Their structure is gene- 

 rally very simple, as in the lowest it has but a single 

 perforated cell wall, termed the "proper wall" ; in 

 compound shells the septum, or proper wall, is usually 

 single, so that that which forms the anterior wall of 

 one chamber serves as the posterior wall of the next ; 

 in more complex forms each chamber has its own 

 proper wall, so that in these each septum or " septal 

 plane," consists of two lamellae, as in Fig. 39. In still 

 more complex forms (Figs. 40, 41) these two proper 

 walls are separated, and between them is developed 

 "the intermediate" or "supplemental" skeleton, 

 through which, if largely developed, ramifies a series 

 of canals containing prolongations of the sarcode, 

 serving to preserve the vitality of the skeleton. 

 Between these " body chambers " a further connection 

 is established by " stolon passages," or bands of pro- 

 toplasm. Thus, in one of the highest members of 

 this .order, we should notice the "tubulated body or 

 proper wall," the "intermediate skeleton," and the 



Fig. 43. — Side and front view of proper wall. From Moebius'' 

 " Memoirs." Plate 33, Fig. 41. 



"body chambers" connected by "canal systems" 

 and "stolon passages." 



Remembering these points, let us turn to Eozoon, 

 and we shall see how remarkably all the typical 

 structures of highly organised foraminifera are so 

 closely simulated, that nigh a generation of geologists 

 were led to accept it as such. Fig. 43 represents 

 Eozoon as usually given in our text-books ; to the 

 naked eye the rock appears as a series of green and 

 white laminae, which on microscopical examination 

 present a structure strikingly like those of the body 

 chambers of such foraminifera as Nummulites"; the 

 so-called " casts of the body cavities " are surrounded 

 by a wall perforated by many minute tubuli or pores, 

 apparently analogous in structure and function to the 

 proper wall of foraminifera. Above this proper wall 

 is a thicker layer of typical calcite, corresponding 

 to the intermediate skeleton, and containing series of 

 "canals" and "stolon passages," or structures 

 apparently similar to them. Thus, we here find 

 simulations of all the typical structures of one of 

 the highest of the foraminifera; proper wall, body 

 chambers, intermediate skeleton, canals, stolon 

 passages — all are represented ; hence, urged Dawson 

 and Carpenter, though we can easily understand that 



