1899] MICROSCOPICAL JOURNAL. 137 



Bennett, G. C. Karop, The Hon. Sir P^ord North, J. J. 

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

 W. H. Dallinger, Dr. R. G. Hebb. The president then 

 delivered the anual address. The first portion was a re- 

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

 he congratulated the society on its improved position; the 

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

 cussed some formula? 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 things that can be readily grasped by 

 any person who has not previously given 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 get the result. 



NEW PUBLICATIONS. 



The Microscope ; Byjabez Hogg. — The fifteenth edi- 

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

 issued by Geo. Routledge and Sons, London. Price, 10 s. 

 6 d. The present edition is greatly enlarged from former 

 ones and contains an immense amount of information upon 

 general subjects. It does not, however, pretend to cover 

 medical microscopy except by giving an account of a few 

 of the best-known pathogenic 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 algee 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 claviger. 



