PEOCBEDINGS OF SOCIETIES. 



RoTATi MiCKOSCOPICAL SOCIETT. 



June Uh, 1873. 

 Chaules Beooke, Esq., F.R.S., President, in the chair. 



A paper was read by Mr. Kitton, of Norwich, on " AidacO' 

 discus formosus, Oniphalopelta versicolor, &c. " giving an account 

 of certain species of Diatomaceae, some of them new, from the 

 harbours of Peru and Bolivia. 



Mr. J. W. Stephenson took the opportunity of stating that to 

 his surprise, he found that the mode of dividing the cone of 

 light in his erecting binocular microscope by means of two prisms 

 was used by Professor Riddell, of New Orleans, in the year 1853, 

 in his form of binocular. The arrangement of that instrument 

 differed, however, from his own in certain respects. He had only 

 just heard of Professor Riddell's invention. 



Mr. Stephenson then read a,paper entitled " Observations on 

 the Inner and Outer Layers of Coscinodiscus when Examined in 

 Bisulphide of Carbon and in Air." The paper introduced a 

 method of " Determining the structure of minute organisms 

 by means of the refractive indices of the media in which they 

 are examined." Attention had lately been drawn to this method 

 by Mr. Charles Stewart, who had applied it to determine the com- 

 position of specules in Echinodermata. Its result in the present 

 instance was to show that the central spot in certain hexagonal 

 areolae of Coscinodiscus was really a perforation and not a de- 

 pression or elevation. 



October 1st, 1873. 



C. Brooke, Esq., F.E.S., President, in the chair. 



A paper was read by Dr. Maddox " On an Organism found 

 in Fresh-pond water." These bodies, found in a small pond in 

 the New Forest, appear to belong to the Protozoa. They con- 

 sist of irregularly circular or sub-globular sarcodic or muco- 

 gelatinous masses, often very bright at the edge, containing small 

 granular or corpuscular bodies of various sizes and of a highly 

 refracting nature, the whole having a very strong violet or lilac 

 tint when seen by transmitted light. The masses differ very con- 

 siderably in dimensions, the smallest containing only a few of the 

 capsules, the largest a very great number. In many of the 

 medium size and most, if not all, of the larger ones, the general 



