CONTENTS. Vll 
PACK 
IV, — On a Large-angled Immersion Objective, without Adjustment Collar; 
with some Observations on “ Numerical Aperture.’’ By John Ware 
Stephenson, F.R.A.S., and Treasurer of the Royal Microscopical 
Society. (Woodcut.) 51 
A’. — The Structure of the Coloured Blood-corpuscles of Amphiumcx trklac- 
tylum^ the Frog, and Man. By Dr. H. D. Schmidt, Patliologist of 
the Charity Hospital, New Orleans, La. (Plate IV.) 57 
Notes and Memoranda 79 
Diatoms in Coloured Liquids . . 79 
Abnormal Appearances of Hydra viridis 80 
Rhizopods in an Apple-tree 80 
On an Ostracode Crustacean of a new Genus {Acanthopus), met 
with in the deep Waters of the Lake of Geneva. By M. II. 
Vernet 80 
A Microscopic Trap for a Rover 81 
High-angled Objectives for Histological Work 81 
New Process of Colouring Microscopic Preparations with a Picro- 
aniline Solution 82 
Amplifiers 85 
Penetration 8G 
llie Genus Ligula .. . . 8G 
Nutriment of Bacteria 8G 
Bacteria as Parasites in Splenic Disease 87 
Bibliography 88 
Proceedings of the Society — 
Qth March, 1878 93 
3rd April, 1878 95 
No. III. (July). 
I. — The Structure of the Coloured Blood-corpuscles of Amphiuma tridac- 
tylum, the Frog, and Man {continued'). By Dr. H. D. Schmidt, 
Pathologist of the Charity Hospital, New Orleans, La. (Plate V.) 97 
II. — On the Present Condition of Microscopy in England. By Frank 
Crisp, LL.B., B.A., Sec. R.M.S 121 
III. — On a Species of Acarus of the genus Cheyletus, believed to be new. 
By A. D. Michael, F.R.M.S. (Plate VI.) 1.33 
IV. — On the Question of a Theoretical Limit to the Apertures of Micro- 
scopic Objectives. By Professor G. G. Stokes, M.A., D.C.L., LL.D., 
Sec. R.S., Lucasian Professor of Mathematics in the University of 
Cambridge. (2 Woodcuts.) 139 
V. — On the Results of a Computation relating to Tolies’ ^ Objective. By 
Professor R. Keith. (Plate VII. and a Woodcut.) 142 
Notes and Memoranda 144 
Lnsect Digestion and Development 144 
Improvements in the Rivet- Leiser Microtome 145 
