PROCEEDINGS OF THE SOCIETY. 745 



Mr. Beck, being called upon to exhibit and describe a new form of 

 optical bench which had been brought to the Meeting for the purpr.se, 

 asked to be allowed to defer the description to a future occasion, as 

 owing to the electric current available not being suited to the lamp he 

 had brought, it was not then possible to exhibit the apparatus effectively. 



Mr. J. H. Agar Baugh exhibited an immersion spot lens, made by 

 Reichert, of Vienna, which was used to show the Brownian movement 

 of very small particles in the blood. This it did very effectively. 



Mr. F. W. Watson Baker exhibited a new metallurgical Microscope 

 designed by Messrs. Watson and Sons, for the use of students ; also a 

 Cathcart Microtome with automatic action for raising the material to be 

 sectioned ; also a Microtome for cutting sections by hand, and a sliding 

 bar stage fitted with ball-bearings. 



Mr. James Murray's paper " On some Rotifera from the Sikkim 

 Himalaya," was, in the absence of the author, read by Mr. C. F. 

 Rousselet, who expressed the pleasure with which he had received this 

 communication, more especially as he remembered only one previous 

 paper upon the Rotifers of India. 



On the motion of the Chairman, a vote of thanks was unanimously 

 passed to Mr. Murray for his paper, and to Mr. Rousselet for reading it 

 to the Meeting. 



Mr. J. M. Coon read a paper " On Cornuvia serpula, a species of 

 Mycetozoa new to Britain " ; the subject being illustrated by lantern 

 slides, and by specimens exhibited under Microscopes in the room. 



The thanks of the Society were voted to Mr. Coon for his very 

 interesting paper. 



Mr. A. E. Conrady gave an account of an early criticism of the Abbe 

 theory contained in a paper published in 1880 by Dr. Altmann, who 

 maintained that the image should be considered as built up of diffusion 

 disks such as Helmholtz had dealt with in his paper of 1878, and that 

 in cases where the objective was not filled with direct light the latter 

 was diffused by the object so as to utilise the otherwise dark space, and 

 that the whole aperture was thus more or less completely utilised, with 

 the result of a somewhat modified form of spurious disk. Altmann had 

 thus tried to extend the Helmholtz theory. 



The chief interest of this paper now lay in the fact that it brought 

 an immediate and very vigorous reply from Professor Abbe in which 

 the latter added very considerably to his previously published account 

 of his theory, and in which he laid particular stress on the difference 

 between a self-luminous object and one illuminated artificially. It was 

 also interesting to note that this was a complete anticipation of Mr. 

 Gordon's " antipoint " theory, so that one might say, that Professor Abbe 

 had replied to Mr. Gordon's paper more than twenty years before it was 

 read. 



