30 PROGRESS OF MICROSCOPICAL SCIENCE. 



appearances as of morphological significance, but merely as physical 

 phenomena, from which nothing further can certainly be inferred than 

 the presence of such structural conditions as are capable of producing 

 the diffraction effects obtained. The remark has notable applications 

 to many of the microscopical researches on markings of diatoms, and 

 on striated muscular fibre. And it affects not merely the morpholo- 

 gical relations of the objects, but the deductions, made from microsco- 

 pical observation, as to properties (such as differences of transparence, 

 colours, polarization, &c.). The author lays down the following prin- 

 ciple as basis for determination of a limit : — By no microscope can parts 

 be distinguished (or the marks (Merkmale) of a really present structure 

 perceived), if they are so near to each other that the first bundle of 

 light rays produced by diffraction can no longer enter the objective 

 simultaneously with the undiffracted cone of light. Professor Abbe 

 has also recently described a new illuminating apparatus for the 

 microscope, formed of a condensing system of two unachromatic lenses, 

 which are fixed in the stage of the microscope, and transmit the rays 

 from the mirror below ; the purpose being that the object (immediately 

 above the upper lens) may be illuminated by light from a great many 

 different directions. 



Is Eozoon Canadense a Foraminifer or not ? — This important ques- 

 tion which was long ago discussed by Dr. Carpenter and Professors 

 King and Eowney, has recently been taken up by no less an authority 

 than Mr. H. J. Carter, F.R.S., who alleges that it presents none of the 

 features of an animal ; he has been replied to in a very able paper 

 by Dr. Carpenter, in the last number of the ' Annals of Natural His- 

 tory.' We propose to lay the former view of Mr. Carter before our 

 readers in the present number, and Dr. Carpenter's in the next number 

 of this Journal. After giving the structure of certain fossil specimens 

 of Nummulites and Orlitoides, he goes on to say, that " in vain do we 

 seek in the so-called Eozoon Canadense for the imvarying perpendi- 

 cular tubuli, sine qua non of foraminiferous structure. In vain do we 

 look for that regularity of chamber-formation which, in the amorphous 

 growth assigned to the so-called Eozoon, might be equally well as- 

 sumed to be identical with the heterogeneous mass of chambers on each 

 side of the central plane of Orbitoides dispansa, accompanied by the 

 transverse bars of stoloniferous structure uniting one chamber to the 

 other. In short, in vain do we look for the casts of true foramini- 

 ferous chambers at all, in the grains of serpentine ; they, for the most 

 part, are not subglobular, but subprismatic. With such deficiencies, I 

 am at a loss to conceive how the so-called Eozoon Canadense can be 

 identified with the foraminiferous structure, except by the wildest con- 

 jecture ; and then such identification no longer becomes of any scien- 

 tific value. Having examined the slice of Laurentian limestone 

 which has been so courteously submitted to me, in thick and thin 

 polished sections, mounted in Canada balsam, by transmitted and also 

 reflected light, also the surface of the 'decalcified' slice as it came 

 from you, in all directions, with one-quarter and one-inch focus com- 

 pound powers respectively, I must unhesitatingly declare that it pre- 

 sents no foraminiferous structure anywhere. Nor does its structure 



