The only remaining theory is that of the filling of cavities by infiltration with serpentine. This accords with the fact that such infiltration by minerals akin to serpentine exists in fossils in later rocks. It also accords with the known aqueous origin of the serpentine nodules and bands, the veins of fibrous serpentine, and the other minerals found filling the cavities of Eozoon. Even the pyroxene has been shown by Hunt to exist in the Laurentian in veins of aqueous origin. The only difficulty existing on this view is how a calcite skeleton with such chambers, canals, and tubuli could be formed; and this is solved by the discovery that all these facts correspond precisely with those to be found in the shells of modern oceanic Foraminifera. The existence, then, of Eozoon, its structure, and its relations to the containing rocks and minerals being admitted, no rational explanation of its origin seems at present possible other than that advocated in the preceding pages. If the reader will now turn to the figures in the illustration on the opposite page (Fig. 59), he will find a selection of examples bearing on the above arguments and objections. Fig. 1 represents a portion of a very thin slice of a specimen traversed by veins of fibrous serpentine or chrysotile, and having the calcite of the walls more broken by cleavage planes than usual. The portion selected shows a part of one of the chambers filled with serpentine, which presents the usual curdled aspect almost impossible to represent in a drawing (_s_). It is traversed by a branching vein of chrysotile (_s′_), which, where cut precisely parallel to its fibres, shows clear fine cross lines, indicating the sides of its constituent prisms, and where the plane of section has passed obliquely to its fibres, has a curiously stippled or frowsy appearance. [Illustration: Fig. 59.--_Figures of various Structures and States of Preservation._ Fig. 1.--Portion of two laminæ and intervening serpentine, with chrysotile vein. (_a_) Proper wall tubulated. (_b_) Intermediate skeleton, with large canals. (_c_) Openings of small chamberlets filled with serpentine. (_s_) Serpentine filling chamber. (_s¹_) Vein of chrysotile, showing its difference from the proper wall. Fig. 2.--Junction of a canal and the proper wall. Lettering as in Fig. 1. Fig. 3.--Proper wall shifted by a fault, and more recent chrysotile vein not faulted. Lettering as in Fig. 1. Fig. 4.--Large and small canals filled with dolomite. Fig. 5.--Abnormally thick portion of intermediate skeleton, with large tubes and small canals filled with dolomite. ]