PROCEEDINGS OF THE SOCIETY. 785 



objects ; and that, when this is the case, the two objects will seem in 

 the Microscope (or telescope) to be farther asunder than they really are. 



These results of the new method are here selected from amongst its 

 many achievements, because they are all susceptible of striking verifica- 

 tion by experiments, conducted upon the exquisite rulings upon the 

 under-side of a cover-glass, which have been produced by Mr. Grayson, 

 of Melbourne. 



The way in which these experiments were carried out, and the 

 apparatus employed, were then described by the speaker ; and he called 

 special attention to the importance of accurately adjusting the distance 

 between the source of light and the condenser ; but the time at his 

 disposal did not admit of his describing how to make this important 

 adjustment. 



In the course of his remarks, he mentioned that he had found details, 

 which he had not seen described, upon the diatom known as Pinnularia 

 nobilis. Each of the tongue-like costse upon this diatom has upon it 

 from six to eight rows of somewhat more closely packed dots, each row 

 extending the whole length of its costa, and the whole presenting an 

 appearance not unlike that upon the tongue-like costae of the more easily 

 resolved diatom sold under the name of Eupleuria pulchella, which seems 

 to be of the same genus as that which Van Heurck calls Entopyla, and 

 figures upon page 340 of his Treatise. 



Finally, Dr. Stoney expressed his readiness to make arrangements, so 

 far as he could, to show the foregoing experiments to any Fellow of the 

 Society who is specially interested in this branch of microscopical study. 



Prof. Everett said that Lord Rayleigh had made reference in his 

 paper (see p. 448) to assistance which had been furnished to him by 

 Dr. Stoney. 



On the motion of the President, the thanks of the Society were 

 unanimously voted to Prof. Everett for his paper. 



Mr. W. Wesche gave' a brief resume of his paper " On the mouth 

 parts of the Nemocera, and their relation to the other families of 

 Diptera," which was illustrated by a number of excellent drawings shown 

 upon the screen by the Epidiascope, the last of the series being coloured 

 to show the homologous parts of the mouth organs in different families, 

 as compared with those of the Cockroach, which was taken as a type. 

 By the kindness of Messrs. Baker, of High Holborn, who lent a number 

 of their microscopes, Mr. Wesche was able to show a number of mouth 

 parts of blood-sucking and disease-carrying Diptera ; amongst them were 

 Glossina morxitans (nagana disease), G. palpalis (sleeping sickness), 

 Stegomyia fasciata (yellow fever), and Anopheles cinereus (malaria). 



The thanks of the Society were cordially voted to Mr. "Wesche for 

 his communication, and the explanation given of the plates which had 

 been exhibited. Also for the excellent series of preparations illustrative 

 of the subject exhibited under Microscopes kindly lent for the occasion 

 by Messrs. Baker. 



