[AO] Reprinted in the Annals and Magazine of Natural History, May, 1874.
The following summary, given by these authors, may be taken as including the substance of their objections to the animal nature of Eozoon. I shall give them in their words and follow them with short answers to each.
"1st. The serpentine in ophitic rocks has been shown to present appearances which can only be explained on the view that it undergoes structural and chemical changes, causing it to pass into variously subdivided states, and etching out the resulting portions into a variety of forms—grains and plates, with lobulated or segmented surfaces—fibres and aciculi—simple and branching configurations. Crystals of malacolite, often associated with the serpentine, manifest some of these changes in a remarkable degree.
"2nd. The ‘intermediate skeleton’ of Eozoon (which we hold to be the calcareous matrix of the above lobulated grains, etc.) is completely paralleled in various crystalline rocks—notably marble containing grains of coccolite (Aker and Tyree), pargasite (Finland), chondrodite (New Jersey, etc.)
"3rd. The ‘chamber casts’ in the acervuline variety of Eozoon are more or less paralleled by the grains of the mineral silicates in the pre-cited marbles.
"4th. The ‘chamber casts’ being composed occasionally of loganite and malacolite, besides serpentine, is a fact which, instead of favouring their organic origin, as supposed, must be held as a proof of their having been produced by mineral agencies; inasmuch as these three silicates have a close pseudomorphic relationship, and may therefore replace one another in their naturally prescribed order.
"5th. Dr. Gümbel, observing rounded, cylindrical, or tuberculated grains of coccolite and pargasite in crystalline calcareous marbles, considered them to be ‘chamber casts,’ or of organic origin. We have shown that such grains often present crystalline planes, angles, and edges; a fact clearly proving that they were originally simple or compound crystals that have undergone external decretion by chemical or solvent action.
"6th. We have adduced evidences to show that the ‘nummuline layer’ in its typical condition—that is, consisting of cylindrical aciculi, separated by interspaces filled with calcite—has originated directly from closely packed fibres; these from chrysotile or asbestiform serpentine; this from incipiently fibrous serpentine; and the latter from the same mineral in its amorphous or structureless condition.
"7th. The ‘nummuline layer,’ in its typical condition, unmistakably occurs in cracks or fissures, both in Canadian and Connemara ophite.