PROCEEDINGS OF THE SOCIETY. 175 



Professor Abbe's paper, " Some Eemarks on the Apertometer " 

 (see p. 20) was laid before the meeting by Mr. Crisp, who gave some 

 demonstrations of the advantages of the expression of numerical over 

 that of angular aperture. 



Mr. A. D. Michael read a paper, " A Further Contribution to the 

 Knowledge of British Oribatidfe " (see p. 32), which was illustrated by 

 diagrams and by numerous specimens exhibited under Microscopes 

 on the table. 



Dr. Braithwaite desired to express the pleasure he felt at seeing 

 such original work in a much neglected branch of natural history, and 

 hoped it would be followed by many more such communications. 



Mr. Stewart asked what plan Mr. Michael suggested as being the 

 best to transmit to him creatures of that kind for examination. It 

 was most likely that they might in the course of their rambles find 

 many of them, and it would be very desirable to know the best means 

 of forwarding them. 



Mr. Michael said if the distance was not more than one or two 

 days' post, they would come very well in a glass minim tube with some 

 damp moss ; if, however, the journey was one of longer duration, it 

 would be better to put them into dilute acetic acid or glycerine. 



Dr. Fripp's paper " On Daylight Illumination with the Plane 

 Mirror " was taken as read. 



Mr. J. W. Groves read a paper " On a Means of obviating the 

 Eeflection from the inside of the Body-tubes of Microscopes, with 

 Suggestions for Standard Gauges for the same and for Substage 

 Fittings, &c." 



Mr. Ingpen said that Messrs. Powell and Lcaland had obtained 

 the result proposed by Mr. Groves by slipping a short piece of tube 

 over the A eye-piece, so that it did not enter the body for its whole 

 length. By this plan tliey also secured the same distance between 

 the objective and the diaphragm in each cye-i)iecc ; this was a matter 

 of some importance, as many objectives would not perform so well 

 with either a longca- or shorter body than ten inches, and tliis arrange- 

 ment also brought each eye-piece into focus on its insertion into the 

 body, and saved the trcjuble of focussing each one separately. With 

 respect to the question of uniformity of gauge, this was doubtless very 

 desirable. The l.\-inch gauge for the substage fittings originally 

 suggested by the late Mr. Kichard Beck was now very generally 

 adojitcd, but it seemed unlikely that tlio various opticians would 

 extend that uniformity to bodies or eye-pieces. 



Mr. T. JefFery Parker called attention to a slide of Bacillus sub- 

 tilis taken from a zooghea film on the surface of hay infusion fifteen 

 days old. The 7^af///t exhibited the spore foruiing condition described 

 by Ewart, the rods having elongated into long boldly-curved inter- 

 lacing iihiments, the protoplasm in which had collected here and there 

 into the characteristic refringent spores. 



