376 PROCEEDINGS OF THE SOCIETY. 



places that it was very difficult to see bow they managed to exist. In 

 looking over some fossils which had been collected during the Indian 

 survey, and which came from a desert and had been kept dry ever 

 since, he found a number of Acari. That they came from India with 

 the fossils was well established, but how they obtained their nourish- 

 ment was a matter of surprise. 



Mr. Crisp, in reply to Dr. Edmunds, described the new IJ-inch 

 screw recently adopted in America for low-j^ower objectives of wide 

 angle, known as the " Butterfield Broad-gauge Screw " (see p. 301). 



Dr. E. Cutter's paper, " On the Infusorial Catarrh of Salisbury," 

 was read by Mr. Stewart. 



Dr. Cutter confirms the view expressed by Dr. J. H. Salisbury in 

 the ' Journal fiir Parasitenkunde,' that epidemic catarrh is due to 

 the presence of infusoria, — Asthematos ciliaris. He maintains that 

 they are not, as some suppose, modified ciliated epithelium, because 

 by culture in mucus outside the body they increase in number in 

 many ways, and they are found in morbid secretion of the conjunctiva 

 where no ciliated epithelium exists. Moreover, those remedies only 

 cure the disease which kill the Asthematos. He states that they are 

 not, as some have insisted, the cause of hay-asthma. 



The President called attention to the di-a wings accompanying the 

 paper, which were of interest in connection with it. 



Mr. Stewart thought it quite possible that the objects represented 

 by the drawings might be epithelial, and yet that they might be the 

 vehicles by which disease was propagated. 



The President said they were certainly a very exceptional form of 

 infusoria, and looked more like the ciliated cells of epithelium ; still 

 it was quite possible that there might be such forms of infusoria 

 as these. 



Mr. Crisp said that the suggestion that the radiation of light 

 was greater in glass or oil than in air, had been supposed in some 

 quarters to be so paradoxical and so opposed to what were regarded 

 as the fundamental laws of optics, that he had brought for exhibition 

 after the meeting a piece of apparatus (suggested by Professor Abbe) 

 which would enable the fact to be appreciated without requiring an 

 eye accustomed to photometrical estimations (see p. 3i3). 



Mr. Shadbolt's " Further Eemarks on the Apertures of Micro- 

 scope Objectives " was taken as read as follows : — 



" I beg to offer a few remarks upon this subject, relative to the 

 point to which we have now advanced in the controversy. 



" My last communication, together with the reply from ' the other 

 side,' appear in the Journal for February, and certainly nothing in 

 the latter can be found which disproves the view I have enunciated 

 on the main point at issue, viz. whether any ' aperture ' of any kind 

 can exceed that of 180^ angular in air. 



" I request attention particularly to the two diagrams numbered 



