SCIENTIFIC SUMMARY. 
327 
primitive mouth, and the development of a secondary mouth. (10) The 
development of a pair of large nerve-ganglia by invagination of the 
epiblast immediately below the primitive eye-chambers. 
Progress of Microscopy during the Quarter. — The following is a list of the 
papers that have appeared in the “ Monthly Microscopical Journal ” during 
the past three months : — 
Contributions towards a Knowledge of the Appendicularia. By Alfred 
Sanders, F.L.S., F.R.M.S., Lecturer on Comparative Anatomy at the 
London Hospital Medical College. — Note on the Verification of 
Structure by the Movements of Compressed Fluids. By Dr. Royston- 
Piggott, F.R.S., &c. — Note on the President’s Remarks on the Searcher 
for Aplanatic Images, as to the Principles upon which it acts. By Dr. 
Royston-Piggott, F.R.S. — On Bog Moss. By R. Brathwaite, M.D., 
F.L.S. — The Fungus of the Hawthorn (Acestelia Lacerta, Tulasne ; 
HScidum Lacertum, Grev.). By Thomas Taylor, Superintendent/^ the 
Microscopical Department of the Commission of Agriculture, U.S.A. — 
Points in the Histology of the Human Kidney. By R. Branwell, 
Brighton. — The Scales of Lepism as seen with reflected and Trans- 
mitted Light. By John Anthony, M.D., F.R.M.S. — Note on a curious 
Proboscis of an unknown Moth. By S. J. McIntyre, F.R.M.S. — An 
Instrument for excluding Extraneous Rays, in measuring Apertures of 
Microscope Object-glasses. By F. Id. Wenham, Vice-President 
R.M.S. — On the Construction of the Dark or Double-bordered 
Nerve Fibre. By Dr. H. D. Schmidt, of New Orleans, U.S.A. — 
The Theory of Immersion. By Rev. S. Leslie Brakey, M.A. — 
On certain Beaded Silica Films Artificially Formed. By Henry J. 
Slack, F.G.S., Sec. R.M.S. — The Suctorial Organs of the Blow-fly. — 
By John Anthony, M.D., F.R.M.S. — On the Use of Black Shadow 
Markings and on a Black Shadow Illuminator. By Dr. Royston- 
Piggott, M.A., F.R.S., &c. — The Theory of Immersion. By Rev. S. 
Leslie Brakey, M.A. — On Bog Mosses. By R. Brathwaite, M.D., F.L.S, 
Microscopic Structure of Irish Granites . — A paper has been published 
on this subject in the “Geological Magazine” by Professor Edward 
Hull, F.R.S. Two granites are described by the author, those of Co. 
Mayo and Co. Wicklow. He says of the first that the three slices 
which were prepared for him “ show the general structure of the granite 
extremely well. With the 2-inch object-glass, and under polarised light, its 
constituents are brought out in their relative proportions ; the most abundant 
mineral being orthoclase, next silica, then the triclinic felspar, then mica, 
and lastly magnetite.” With regard to the silica, he says that, as usual in 
granites, it forms the basis in which the other minerals (felspar and mica) 
are imbedded. It is itself without crystalline form, receiving only the forms 
given to it by the sides of the felspar crystals $ and with polarised light the 
boundary edges are often seen lined by narrow parallel bands of different 
prismatic colours. The interior portions exhibit, on rotating the analyser, 
the usual gorgeous shades of colouring, one colour sometimes imperceptibly 
shading off into another over the fields of view, like the blending of the 
colours in a rainbow. With the |-inch object-glass the silica is seen to be 
highly cellular, and fluid bubbles in some of the cells come into view. With 
