120 PROCEEDINGS OF THE SOCIETY. 



improve the present design by placing a concave mirror not opposite 

 to but behind the lamp, so as to obtain more light on the object. The 

 mirror at 45° placed below the object-glass was simply a plain cover- 

 glass not silvered, and this had been found to be quite sufficient for low- 

 power magnification, but did not give such perfect illumination as the 

 silvered glass placed half through the objective at an angle of 45°. As 

 stated previously, the novel and useful departure in this class of Micro- 

 scope was the arrangement in which the electric illumination was fixed to 

 the object-glass itself. 



The Chairman said it was not necessary, after the appreciative way 

 in which Mr. Stead's paper had been received, to pass any formal vote 

 of thanks. The Society was indebted to him not only for his paper, but 

 for most interesting demonstrations in former times on the methods of 

 preparing and examining metals under the Microscope, the importance 

 of which was becoming more and more fully recognised. Quite recently 

 he met with a notable instance, showing the value of microscopical 

 examination. A large manufacturing firm found that the metal they 

 were using was splitting during the process of manufacture. On subject- 

 ing it to chemical examination, they found that the ingredients were pure 

 and the alloy was correct, so twenty minutes were spent in cutting and 

 polishing a specimen and examining it under the Microscope, with the 

 result that the trouble was at once located. Investigation showed that 

 a workman in one department had been annealing the metal badly, so 

 that another man should get into trouble when it came into his hands 

 for manufacture. This was only one illustration of the value of this 

 method of testing metals, and no one had been more prominent in 

 furthering this kind of research than Mr. Stead. 



The Rev. Eustace Tozer read a paper on " Mounting Rotifers and 

 Protista in Canada Balsam," which he illustrated by a number of 

 specimens exhibited under Microscopes in the room, including Brachionus, 

 Floscularia, Hydatina, (Ecistes, Pterodina, Euglena, ciliated embryo of 

 Membranipora pilosa, Polytoma uvella, etc. 



Mr. Charles S. Bright suggested that instead of oil of cloves, cajuput 

 oil should be used, as being less liable to oxidise, and also much more 

 absorbent of alcohol, one volume of cajuput oil absorbing from seven to 

 nine times as much alcohol as the same volume of oil of cloves would do. 

 Oil of cajuput has a greater affinity for Canada balsam, belonging 

 chemically to the same class, Canada balsam being of the terebene or 

 turpentine series, .which includes cajuput, lemon, orange, citron, 

 cedrat, etc. 



Mr. Rousselet said he noticed Mr. Tozer spoke of using osmic acid 

 first, but he had always found it necessary to narcotise the Rotifers with 

 cocaine first, otherwise they would at once shut up. He had prepared a 

 few notes on the subject of mounting Rotifera, which he proceeded to 

 read as follows : — 



The difficulty of mounting Rotifera in media appreciably denser 

 than water, such as glycerin or Canada balsam, is well known to all who 

 have made the attempt. This difficulty arises from the fact that the 

 body of a Rotifer is a closed vesicle containing a perivisceral fluid of 



