1899] MICROSCOPICAL JOURNAL. 137 



Bennett, G. C. Karop, The Hon. Sir Ford North, J. J. 

 Vezey; Treasurer, W. T. Suffolk; Secretaries, Rev. Dr. 

 -W. H. Dalling-er, Dr. R. G. Hebb. The president then 

 delivered the anual address. The first portion vi^as a re- 

 view of the work of the past year, in the course of which 

 he cong-ratulated the society on its improved position; the 

 second portion was a paper on Dispersion, in which he dis- 

 cussed some formulae necessary in constructing- achroma- 

 tic lenses ; diagrams and tables in illustration of the sub- 

 ject being- thrown upon the screen. The mathematical 

 calculations involved in questions of dispersion and refrac- 

 tive index not being- thing-s that can be readily g-rasped by 

 any person who has not previously g-iven much attention to 

 the subject. Mr. Nelson put before them a method of 

 measuring- refractive indices by which the calculations 

 could be made much more easily than had before been pos- 

 sible; now it was only necessary to measure two lines in 

 the spectrum, and apply his formula to g-et the result. 



NEW PUBLICATIONS. 



The Microscope ; By Jabez Hogg. — The fifteenth edi- 

 tion of this work which first appeared in 1854 has just been 

 issued by Geo. Routledg-e and Sons, London, Price, 10 s. 

 6 d. The present edition is g-reatly enlarg-ed from former 

 ones and contains an immense amount of information upon 

 g-eneral subjects. It does not, however, pretend to cover 

 medical microscopy except by g'iving- an account of a few 

 of the best-known pathog-enic bacteria including- B. an- 

 thrax and B. pestis. It is admirably illustrated. 



Coccospheres and Rhabdospheres. — Both these are, by 

 G. R. Murray and V. H. Blackman, now placed among- 

 the algae and described as "free, unicellular bodies, pro- 

 vided with an outer covering- of calcareous plates, free 

 from overlapping-, or readily separable from each other, 

 the plates characterized by symmetrical excrescences or 

 markings." They are placed in the family Coccosphaera- 

 ceae. The Coccospheres are : C. pelagica and C. leptopora 

 and the Rhabdospheres are either R. tubifera or clavig-er. 



